We've got a Bongo (2 wheel drive and considerably better on mpg than the example cited by Eric above). Depending on the conversion (and the size/age of the kids) you can sleep four (two in the van and two in the poptop) but it would be extremely cosy. The answer, of course, is a driveaway awning, which should only take a few minutes to put up and means you get to keep your pitch when you nip into town. Bike rack on the back is a good addition too.

You can pick up Bongos for the sort of price you're looking at, but they may be a bit frayed around the edges. Mine was imported from Japan and cost £5000 - ten years old, in fantastic nick, with very low mileage. The price rocketed dramatically when I paid for a full conversion.

The other bonus is you get to join the only vehicle owners club named after a Frank Zappa and Captain Beefheart album - Bongo Fury. Plenty of useful info (too much, some would say) and a for sale page on the site, where there's a fair frew for sale in your price range. Useful stuff in the forum. And you can get to refer to yourself as a Bongonaut.

And they're lovely to drive.