Personally after owning a 250 and now having 2 350's, I'd opt for the 350 as stated above. Currently, Ford has the biggest gas motor and will tow the RV in question w/o a problem. Should you decide to go w/ Ram or GM, get the biggest gas motor each offers. Regardless of which brand you end up with, the gassers will turn higher RPM's overall (especially on hills) but will get the job done.
Had 2 short box trucks which I loved and now have a dually. You can easily get by w/ a SRW as long as your under 15k total RV weight. Been many debates on a slider hitch or not w/ shortness and in the end, it's up to you. Had a slider when we 1st got into RVing back in '05, used it 2x in 10 years. My belief is that if your that tight, pull forward to straighten out VS trying to get a lil more and risk popping out back window. I DO miss the short box, but also like the extra room of the long box. If money was no object, the DRW would be used to haul the RV and a short box would be my everyday cruiser. Can do it w/ the DRW, but the short box makes things easier.
