When I get asked why I didn't get a diesel, my answer is,
for less than 7000lb travel trailer, really don't need the extra power, nice to have diesel, but not really needed. you can easily get by with 1/2 ton and until recently, no diesels in half tons.
for 7000-10000lbs travel trailer, 3/4 or 1ton recommended, gas or diesel, if towing very many miles, especially mountains, favor diesel.
over 10,000lbs I would be looking at diesel 1 ton. Yes, I know an F150 can tow more than 10000 lbs. I would still be looking at 1 ton diesel.
These are just my personal guidelines and not hard rules. Obviously, whatever you are towing should be within the tow rig specs and provide a safe, enjoyable towing experience. There is nothing good about arriving at a camping spot completely stressed out and exhausted because you don't have the right tow vehicle.