It’s not a wise choice to follow the Park home route, often the sites get sold on to new companies, and with it come new contracts to agree to that can be far more expensive and restrictive to the original contract you signed when you bought your Park home new.
If you disagree regarding the new contract and decide not to sign it, then you will be left with very little option but to remove your home from the site, no matter how old it is or how long it has been there.
This is where your problems will really start, finding another site that will agree to take a Home that they have not actually supplied themselves is as rare as Rocking horse Poo!
Sites make most of their profits from the actual sale and set up fees of selling the Home itself, and pitch space is precious to accommodate new sales. If you take a look on EBay, it is shocking just how little secondhand homes that are still in very good order actually sell for, some only sell for around 2k, and most people who buy these are people who have land available to site them under temporary planning permission whilst they develop a Traditional home of their own on Site.
You also mention renting out to give you an income when you no longer required it for the week yourselves. Sadly not everyone cares and respects other people’s property, and damage an theft of contents on sites by some Hirers is disgusting and very upsetting for the owners indeed, and not everything will be covered on you insurance, which is even more expensive when you enter the Holiday rental market.
I agree that the best way to go if you decide that a Caravan would be useful in this situation would be to follow the previous suggestions of finding a Seasonal long term pitch and buying a decent sized winterised Touring Caravan, designed for 4 Season usage to place upon it.
You can even get a Towing service to move it for you should you ever need to move to a different area, and set up and pack away is an hours job and completely DIY, probably even quicker the more experienced you become. Insurance is fairly reasonable too, and once your pitch fee is paid, all facilities and onsite utilities are usually free and included in the price.