They are expensive but I have a mate who has one and they dont seem to depreciate! He got one a year old and it seems the rate of inflation of the the new model price gets offset by the depreciation of 2nd hand. So in 4 years he has been offered exactly the same price he paid for it. I wish my car was like that. If you can afford one go for it, in the long run it might cost more but I bet you will loose less than if you buy a car even 1/3 the price and sell it 4 years later.
We have VW T2 Camper and a bell tent and we book pitches "for a large tent". We (4 of us) do sleep in the tent
So far this has never been questioned by campsites.
That might change when the kids are old enough to sleep in the tent on their own, at which point the wife and will go back to sleeping in the van.