If you look at the load ratings of the Dextar wheels, I wouldn't be afraid to put them on a 3600lb truck. They have a 3750lb rating per wheel, I think they'll more that do the job.
I've heard the idea that trailer wheels aren't made for cornering, etc... quite a few times. Have you ever seen tandem trailer axles binding when going around corners? Or how about swaying while going down the road? Seems to me they do quite well with cornering and side loads.
http://www.dexstarwheel.com/products.pdf
