Surely the whole point of having a motorhome is to wild camp? Spend the day somewhere (next to a beach) then find a discreet spot to overnight. Otherwise a caravan is a better option. Motorhomes are designed for it - solar panels, large on board water tank, leisure battery, large waste tank. We’ve had motorhomes over 10 years now, in total we’ve clocked up 2 years worth of over nights. I can count campsite over nights on one hand. Once because we visited my folks who have a caravan so all stayed on a site. The other time was because the aire (France) was more expensive and vans packed in like sardines. The campsite next door was cheaper and we had loads of space.
I’d suggest checking out apps like park4night, search4sights and camper contact. Also check out Brit Stops. There are various Facebook pages like sleepy spots. Also forums like motorhome fun.
We always always always, do a little litter pick and aim to leave a wild camp spot tidier than we found it. We always ditch our toilet and waste water responsibly.
Personally I’d avoid Cornwall and Devon peak season, too busy and problematic for wild camping. We’ve successfully wilded there over the winter with no issues. Instead I’d pick less touristy but equally stunning spots like the Northumberland coast.
In terms of accessing smaller roads etc - it’s all down to the skill and confidence of the driver. Our van is over 7 metres in length and over 3 in height. It’s never stopped us going anywhere (we have stickers on the sun visors with height just in case we spot a low bridge sign and ‘forget’ how high we are). We’ve done narrow tight cities and parked up on street to wonder round. Numerous tight twisty mountain roads. Single track, narrow lanes. We live up a very narrow steep lane anyway. On-street parking isn’t really an issue. The modern motorhomes are designed to manoeuvre on a six-pence!! In fact it’s easier to manoeuvre our van than my car. It does have a huge engine which helps on the super steep climbs. You’d have to drop our old van into 1st to cope!!
In terms of packing up - I don’t get it. Motorhomes are designed that you have to put stuff away when you’ve finished with it? Even in our big van space is still a premium. I’d recommend kitting it out with fiamma gadgets - their kitchen cupboard stuff is fab. Plate holders, cup holders etc. Admittedly we have one with fixed beds which makes life easier!! But you literally use something and put it away. We have lots of baskets in the cupboards as it’s easier to store stuff. Likewise large crates in the garage. If you have a garage, again, fiamma do lots of great gadgets to maximise the space and enable you to batten stuff down for travelling.
I’d highly recommend carrying a separate container for drinking water - we have a large BPU free flexible container which we keep in the shower tray for drinking water. You can’t always garuntee how safe the water is that you fill up the onboard tank with. It saves having to put chemicals in to keep it ‘safe’ to drink.
I’d also recommend converting one of your gas bottles to a gas-it system. That way you can fill up at any service station which sells LPG. It’s saved us a fortune over the years and paid for itself pretty quickly. It also has the added benefit when you’re abroad of not running out of gas - each country has its on different type of gas bottle/ fitting.
I’d also suggest buying a large black plastic Jerry can. Then if your toilet starts getting full, tip it in there until you find a chemical disposal point. They can be few and far between here. We’ve just swapped over to a bacteria system, so can now dispose of our toilet down a normal toilet.
We can get 4 nights off one tank of water (3 of us showering daily, washing up for 3 daily meals). The solar panel keeps the leisure battery topped up.
Get some silver screens. They are like a sleeping bag that goes over the windscreen and side cab windows. They make a huge difference for colder nights and help keep the van warmer and are brilliant when it’s baking hot at keeping the van cooler. They are pricey, but worth it for the added comfort.
Lastly when you can. Get yourself to France, Spain and Germany. They are blooming marvellous for motorhoming. You’ll realise how shit and backward England is!! In France virtually every town, village and city have an ‘aire du camping-car.’ It’s a set aside area for people to overnight, usually with facilities to empty toilet, waste tank and fill your fresh water. In France they are generally free. The apps mentioned above detail them. But you can also buy books from Vicarious (google them.). Wild camping in France is much easier then England. Germany have a similar system called Stellplatz. You tend to pay for them BUT the cost of diesel is much cheaper than here and France, so it balances out. I can’t remember what they’re called in Spain - but again a great network and wild camping is widely tolerated.
In the U.K. Scotland has a much better approach to wild camping. Stay away from the honeypot areas in season like the West Coast, Highlands etc. Galloway is awesome and benefits from better weather due to Gulf Stream proximity.