pscaravan,
I think the easiest thing to do is to:
First, pick out the trailer you want.
Second, pick out the tow-vehicle you want.
It's much harder to pick the tow-vehicle first (unless you just buy the biggest diesel pickup truck they make which can just about tow any trailer) and then try to find a matching trailer.
Once you decide on a trailer and find out how much it truly weighs, it will be really easy to see what tow-vehicle you need. The forum members here will be able to give you many, many real-world-experience suggestions.
Good luck and have fun window shopping!