Allen, a fifth wheel owner who contributes to another forum has this info for you......... "calderleisure and niche-marketing.net both do 5th wheelers that can be towed by uk pickups although i would not recomend a nissan as a tow truck, the best ones are the toyota , isuzu and ford. I used to have a nissan and hated it, it was fine on the flat but dont show it a hill.
the 5th wheel company in wales also do a nice unit but only go for one of those if you are going to buy an american pickup, they are way overweight for a uk one and spoil what should be an enjoyable experience (one of the reasons you see quite a few of them on ebay)I have known a couple of people that have had to change their pickup for a yank one because of the weight/towing problem.
A proper weight/tow ratio outfit will use electro magnetic brakes not air brakes like the welsh company do, and the pin weight needs to be under the carry weight of the loadbed area, with a 5th wheel hitch capable of handling the overall weight."
Im not sure that im allowed to tell you here which other forums this person uses but if i cant, Mr Moderator, can you give Allen my Email address and i can point him in the right direction