Trailer tents are quick to erect and are easy to find cheaply on the SH market but you've a hard task ahead convincing your OH that it's better than that lovely, warm, dry cottage or B and B. This year I've seen a lot of small day/camper vans pulling trailer tents.
I had the same DIY idea when I wanted to buy a horsebox. Rather than buy and old box for an extortionate amount of dosh, I bought a much newer wagon and fitted it out myself. A hell of a lot cheaper.