Should I Diesel?

Looking for opinions.
I have been shopping for a new tow rig for 5500lbs camp trailer, with gear about 7k, for a couple years. This is for family of 4 long national park road trips, and hauling open car trailer (4k ish) around the country. Right now we tow with a Sequoia, which works fine, but gets 8.5mpg if I am very careful (60ish, slow up hills), and 13mpg with the car trailer. I have been looking at the baby GM Diesels, used with 60 ish K miles.

The concern going that route, it would also need to be my daily driver, about 10 miles per day in 2-3 mile increments, which sounds hard on a diesel.

Other options, if it was purely a tow rig would be to get an older 3/4ton, totally overkill, but thinking it would still get 14ish with the low loads? Looks like the best option here would be the 07-08 GM, which is tough to pay as much as a 13-14, but seems like its the goldilocks of reliability/no def.

I do all my own maintenance/repairs, but haven't owned a diesel, and parts sound expensive. If it was only a tow rig, it would only do 5-10k ish miles per year.

Should I go Diesel, or should I just suck it up and pay the fuel bill on a 6.0 Tahoe (wifes pick) when we need to tow? Considered a Powerboost so we have a generator when we need it, and hybrid around town or short trips would be ok mpg then. Diesel around me is $0.50-$1 more per gallon then regular.