Before we bought the motor home I was towing a 20 foot TrailManor TT that weight about 4,100 pounds loaded and wet. I started out towing it with a 2002 Chevy 1500HD. This is a crew cab truck with a 6.5 foot bed. I had no problems towing.
Then I got a 2008 GMC 2500HD long bed. It was so much nicer to use as a tow vehicle. I did not tow with a WD hitch for either truck. Under some road conditions I was getting a little bit of bouncing bronco effect. This went away when I switched to the longer wheelbase. The built in brake controller worked so much better than a Prodigy.
If I was going to tow again this is how I would select a tow vehicle.
1. make sure the load carrying capacities are at least adequate.
2. I would require a built in brake controller.
3. I would get the longest wheelbase I could find.
I was towing 180 miles each way, sometimes in heavy commute traffic. Then maximum speed limit while towing is 55 mph. We camped about once a month during Spring, Summer, and Fall. If I was only towing shorter distances then I might relax some of my requirements.
If your wheelbase is too short relative to the length of the TT then you will encounter the "tail wagging the dog" effect. I did not notice this with the shorter wheelbase 1500HD. In my experience the wheelbase of the 1500HD is more than adequate. I have no experience towing with anything that has a shorter wheelbase than that. I doubt that I would want to.
I prefer gas over diesel unless at least one of the following criteria are met:
1. frequently towing above 8,000 feet.
2. towing at least 15,000 miles per year, year after year.
3. towing heavy, but I have no definition of heavy, other than 4,100 pounds is not heavy.
Somewhere I have read about a rule of thumb for wheelbase. I THINK it is that the TV wheelbase should be at least 1/3 of the wheelbase of the trailer you are towing. Perhaps someone else has access to that rule of thumb.
Wayne in Coarsegold near Yosemite
2013 Forest River Solera 24R
2014 Jeep Wrangler Rubicon
ATV trailer for the following toys
2008 Yamaha WR250R,2009 Honda CRF150F
2008 Polaris Scrambler 500