To think this is unfair? Holiday.

Have you tried outright telling her you would prefer the second one because of the location, and the fact you have always treated her to the nicer one before and thought this was her doing that in return?
This.....however ......
clearly your mother thinks she's entitled to have the better accommodation. Since she's paid this time she feels even more entitled - she knows full well the second van is a nicer location.
This too!

The simple solution would be not arriving until check in time for caravan no 2, then you go straight to no 2 and get the dogs settled in there.

I would make this the last joint holiday you have. Next time, book yourself a lovely caravan in a nice spot, no arguments, no sulking, just rest and relaxation for you and the dogs. Tell your mum that this will be the last time, because you are fed up of always having second best accommodation, regardless of which one of you is paying.

@Chefpig clearly your mother thinks she's entitled to have the better accommodation. Since she's paid this time she feels even more entitled - she knows full well the second van is a nicer location.
Think you have to suck it up or not go at all. She won't be changing her mind.

Op surely the quiet one is better for the dogs and walking them on the beach. Remind her of all the times you have paid for her to have the nicest accommodations and surely after 15 years of you compromising you deserve it. Otherwise there really isn’t any compromise it’s mum getting the best every time. Next year I would either pick the better one or leave her at home. There is no enjoyment with someone who is this selfish mother or not.

Have you tried outright telling her you would prefer the second one because of the location, and the fact you have always treated her to the nicer one before and thought this was her doing that in return?

Going forward if you ever go again I would suggest you book and pay for yours, and she books and pays for hers. That way you both get what you pay for and it’s fair.

Do you actually enjoy spending time together? Does It actually matter who gets what caravan unless there are practical implications e.g. someone needs to be closer to the toilet block. It sounds like a childish disagreement between people who don't actually want to holiday together.

Have you thought @Chefpig that your mum might of actually booked that caravan on purpose for her.

Is it just the two of you plus dog/s as it seems strange to pay for two sixth berth vans for 2 people?

Next time both of you should just book your own accommodation.

I also don't get that you mention you book her the better accommodation each time. If you are then going to moan about it then book the same grade for you both

If you are convinced you want the second caravan, due to location, (assuming there won't be much difference in the quality of the accommodation), why not just say you'll let her have the first van so she can get settled in/be closer to facilities etc. Keep repeating "Your caravan" when talking about it.

Just get there before she does, but at a time that allows you to choose.

Did you read the OP? That's not what the issue is.

with say haven you can pay to pick check in times or you’ll get a random time anywhere from between 12noon - 6pm. £20-£50 to pick your time depending on the time you pick.

Unless you request the caravans to be near each other they will again just be randomised or you can pay to pick exact locations.

Late check out is being trialed but that’s a paid for extra around £15-£25 depending on site.

So no you don’t get to stay later just because check in is later.

You will be allowed on site from around 11am though technically the terms and conditions state no more than 2hours before your check in but nobody checks.

As far as the holiday provider is concerned tho ops dog should be in whatever caravan has actually got the dog registered to it and it should only have the registered number of guests.

For fire purposes knowing who is meant to be where and also sometimes you might get an upgrade and if the caravan is pet friendly but no pet registered they could be upgraded to a non pet friendly higher grade because they are not expecting any pets to actually be inside.

it's weird that they'd have caravans that far apart and with different check in times under the same booking.... and with different times does that mean people paying the same don't necessarily get the same amount of time, or does late check in mean later check out too?

Anyway, just tell mum "I'll the second caravan as it'll be much easier to take the dogs out early without disturbing anyone/ You take the first one and you can settle in while I take the dogs out after the journey" Both reasons make more sense than hers.

Also if it’s a haven holiday you don’t have to arrive for check in. The caravan will have a sticker over the door and your welcome pack inside. You don’t need to go to reception.

Why are you being such a martyr?

Use your words or stop going, sounds awful all round.

You are being a total drama llama. It’s your mum you are going on holiday with. 😳. How different can 2 caravans be and why does it matter.

if your mum paid she gets the caravan she wants - you take the other and be gracious
ring the site and ask which van has earlier check in - if it’s the one mum wants - you can take the dogs on a nice walk until the other is ready ?

That’s what I thought too. Normally there are set caravans for dogs.

Your mums paid she gets to choose. I’d be glad I was getting a holiday. We got to static caravan sites so I know the layout and locations can vary massively. Is there no way you can arrive late for the first caravan if that makes sense?

Don’t dance around the issue, just state ‘It feels like you’re insisting on this so you have the better caravan again’.

Can you tell her your dogs need the one with better access to beach so you’ll be taking that one?

Please never pay for her holiday again, she’s a selfish twat when it’s supposedly her treat to you for once.

You paid for her for 15 years and stayed in lower standard caravans yourself for financial reasons, and your DM accepted that?

Understandable you’re resentful. Seems a case of giving to your DM and partner more than you really wanted to, for a long time.

It was sadly unrealistic, given the background, to believe her initial offer of giving you the choice of caravan.

On this specific occasion she’s paying so gets first choice. (Unfair as it is given the background). If you’d like a holiday you’ll still be near the beach, wildlife and things and can try to enjoy it.

I think it might be time to knock this annual ‘holiday’ on the head.
As it stands for this year though, I know your mum has paid this time but I’d be saying I’d really like the better situated caravan because it will be better for the dogs and less disruptive to other people around.

Sounds a nightmare trip every year to me. I wouldn’t be paying for, or going away with, someone who sulks if they don’t get their own way.
As for the set up, personally I think you’d be better off with the quieter caravan with dogs simply so if they’re barking etc they’re not disturbing other people in the vans nearby.