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...
I would say you're approaching too long and too heavy for a srw. Not there yet, but getting close. Definitely at least consider diesel too, for your own towing satisfaction.