We have a 2013 27-5L, loaded ready to camp it weighs in at 11500# with a pin weight of 2410#. We boondock almost all the time. That's pushing our 2002 F350 7.3 6 speed right up to the limit on the combined weight rating and about 600 over on the vehicle weight rating. I have done a bunch of mods to my truck plus a PHP Hydra Chip. I can pull some long steep hills in 4th and overdrive maintaining 55 to 60 mph most times, EGT is the limiting factor here. The trucks suspension takes the weight well, the rear drops about 4 inchs which levels the truck out since the 02 F350 4x4 has the big blocks under the rear springs anyway. It never bottoms or sways, the 5ver tows like a dream back there.
Bill