You are going to be going through some really windy areas and longer wheelbase of a truck would be helpful. I think that's going to be the biggest issue other than the sheer power to pull over the mountains.
If this is a one time thing, I suppose you will survive with the Grand Cherokee V8 as long as you plan to drive really slow 55-60 in the wind.
I'll also tell you that after one experience in the wind in Eastern WA, my wife was not willing to drive while towing the 24 foot trailer that we had at the time with the Expedition. BTW, she made it about 2 miles after the rest area. For the record, she drove the Class A that we moved to later with no worries in similar wind and also the previous F350 with Truck Camper and now the F450 with the same Truck Camper with similar winds.
'10 Ford F-450, 6.4, 4.30, 4x4, 14,500 GVWR, '06 Host Rainer 950 DS, Torklift Talon tiedowns, Glow Steps, and Fastguns. Bilstein 4600s, Firestone Bags, Toyo M655 Gs, Curt front hitch, Energy Suspension bump stops.
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