Interesting discussion. I know that with the exception of the Escape
5th wheel, all of the recommendations are coming from people who do not currently tow a fiberglass 5er and none seemed to indicate any awareness of bed rail clearance issues.
We currently use a 2001 Toyota DoubleCab PreRunner with the 3.4 as our tow and it's only now getting broken in - should pass 200K miles this next week. I have been looking around at what the next tow will be and would like a full size half ton simply for cab space & potential ride improvements but bed rail heights become an area of concern.
My ideal would be a doublecab, 4.0 with 6 speed manual and the long bed, but neither Toyota or Nissan seem willingly to build that combination.