I am casually truck shopping (waiting for 2014 models) and trying to fit a tow vehicle to a future 5th wheel. Most of the 5er models we like are in the 9000lb-11000lb dry weight and 12000lb-14000lb G...
We have a 35' 5er in that weight range and tow behind a 2012 F350 SRW. And behind a 2007 F350 SRW before that. Tows great. Stability no problem even in high winds or large trucks passing. Just make sure the pin weight is ok for the truck rating. Two 5ers of the same length and weight can have pin weights vary 200-300 pounds or more.