I’m no motor head either but my dad is………..so I’ll shoot his experience toward your consideration.
Dirk is right about the towing or working performance of the 6’s out there. They just don’t sport the torque and have to work harder than an 8, therefore having an immediate strain on economy. I can’t speak for all brands but I’ve been hearing well of the newer Fords with the 4.6 V8, regarding overall economy. Maybe a smaller 8 would be a better option.
I did well with a 5.3 in my Tahoe but it was consuming oil like crazy! No drips, stains, leaks, no blue puffs when ya start it…………..but every 2000mi was another quart low!
The best thing you can do is read. Start researching reports and consumer facts and see what stacks up as the best suitable choice. But a 6 would surprise me to be your fit. You’re pulling a load more often than the average guy and harder worked engines wear out quicker. A lot of times the transmission that comes with a 6 is less than you’d desire as well so keep that in mind.
Good luck on your quest!