For the gas RV Fifth Wheel Hauler's out here.

carringb wrote:
Funny that everybody here is screaming for diesels.

By far and large, most motorhomes on the road come with the V10. The larger F53s are good for 30,000 combined.The 450 V10 is rated for over 20,000 pounds towing.

I just hauled back another one of our broken diesel trucks (an '08 F550 with only 124,000 miles), from the Bay Area to Portland, using my trusty V10 with 445,000 miles which has never left me stranded.

#1 reason to go with a diesel: *OMG downshifts!!!!*

Granted, towing 17k at elevation frequently would be a good reason to need forced induction. Occasional towing in New England? A gas engine will pull every grade and still keep up with traffic...

To each their own. Btw that many miles on a gas engine is an anomoly not the norm. It's pretty much an anomoly on any passenger vehicle gas or diesel.
But we're not talking about how they fare 400k from now, OP basically asked what was the best tow rig for her setup and toting around a 5ver that could tip the scales at almost 9 tons is a diesels job and if you don think a 6.2 gasser Ford would struggle big time with that, you're just turning a blind eye to it. Plus the exhaust brake is a big bonus towing in the hills (New England).
I've had 2 6.2s in my company trucks and they're great engines IMO, but I've hooked 14-15k flat beds with no wind resistance and that's a lot for that engine. I only had 3.73s but still. I was at sea level, no head winds.
Additionally, used Cc 4x4 newer dually gassers are almost non existent and new is pretty much a special order. So not Much to choose from.