Eddie has a simlar point to what i was making before Frank got his knickers twisted in his sporon.
The 300 series discos suffered both poor towing stability and lack of power for towing.
The other Clive also has hinted at fuel consumption with his daughter's Cherokee.
For 6K you are looking at a tired 4X4 with what ever you see. Only Hyundai or Diahatsu's offer younger vehicles in that price range. Jeep V8 gas converted machines are ok but then your a little restricted on where to fill up and soon the chancelry will tax LPG and bring it in line with all other fuels.
Unless you particularly "need" 4 wheel drive and a low ratio transfer box then maybe a large people carrier would be more "practical". For example, even towing a large van like I do, I haven't got stuck on any site as such, a bit of wheel scratting does happen on non tarmac drives but only a minimal amount.
The same could be said about fuel consumption. In my case, I do more miles solo and at about 48Mpg I get good value. Sure towing at 30Mpg is a large drop and a sizeable cost to consider when you have the van on the back, but when you consider that two thirds of a week away is spent driving solo, I think the costs still come out in favor of the car.
All I'll say is the choice is yours. But I would try towing with any vehicle you buy before you commit to parting with your reddies. If the vehicle doesn't have a tow bar that you are viewing, I'd find one that does and ask the owner if they would pull your van for you so you can get an idea of how it tows. Obviously a few quid will have to be exchanged but it would be cheaper than a 6k mistake.