When my wife and I were younger and did silly things with our money, we decided to buy a 6 berth overhead bed motor caravan. Although we could often enjoy up to12 weeks holiday a year (the benefits of time off in lieu) we could still never use it enough to match the money outlay. When at work it was just a dead lump because we couldn't use it for anything else.
So we sold it and bought a Ford Transit sized motor caravan, which could be used as a 'car' if we needed too. That worked out much, much better. We no longer motor caravan, but if we did think of doing it again we would settle for a towing caravan. The downside of any motor caravan (as we experienced it) was that if you are on a site, want to stay there a few days and also want a vehicle to explore the area as well, it can become a 'tortoise' on wheels, you have to take everything with you when you go out. In a caravan, you just leave it where it is and can use your car as normal. We did this as well and then found out that the best thing was to leave it on a site for perhaps a season, or a couple of months or so and use the car to go back and forth to it. So many variations to consider!
We still know a bloke who used his own Ford Transit van as a Courier. He had windows fitted, did the floor and van walls and could turn his empty van into a motor caravan in a couple of hours. He bought a free-standing bed, a free standing kitchen, wardrobe, carpet, etc and when not in use he kept these items in his garage, He would then just bung them in his van and secure them to the van walls to ensure they never moved about and bingo, instant holiday mode! A clever man, his vehicle had two uses, saved him I'm sure loads of money.