There are two rules of thumb I've read.
The most common, and most conservative, says you need 110" of wheelbase for a 20' trailer and 4" additional wheelbase for every additional foot of trailer. That says I need 170" for my 34'11" trailer, or a crew cab/long bed.
Another is from one of the RV driving schools, which I forget, but I consider it a bit optimistic. It says the tow vehicle wheelbase should be at least half the distance from the center of the trailer's ball coupler to the center of its rearmost axle. That says I need 140", or an extended cab short bed.
Splitting the difference, I need 155", which is a crew cab/short bed or extended cab/long bed.
I think a good compromise is to take the former, and use 110" for 23' plus the 4" for each additional foot of trailer. That comes out right at the 158" of my extended cab/long bed.
These are based on a normal rear overhang, which is shorter these days than it was years ago, and not something like an extended van with huge overhang.
The longer the overhang, the more leverage sway has to act on the tow vehicle, and vice versa. The longer the wheelbase, the less leverage sway has to act on the tow vehicle, and vice versa.
Look at the trailer's GVWR, not it's unloaded weight, and expect tongue weight to be about 10% of that. The tow vehicle's actual wet and loaded weight (passengers and cargo) plus the GVWR of the trailer, shouldn't exceed the tow vehicle's GCWR. The less it is than that, the easier time the rig will have in the mountains.
The tow vehicle's wet and loaded weight, plus the tongue weight shouldn't exceed the tow vehicle's GVWR.
Forget tow ratings. All they are is the GCWR minus the dry, unloaded weight of the tow vehicle, sometimes with one very light driver. They don't even consider tongue weight.
Here's all the info you need about Fords
EXCEPT the actual weight of the vehicle you're considering, with all its options, and the people and cargo you'll put in it. Make a stop by the nearest CAT scale
part of the test drive. Others can give you the links to Chevy and Dodge.