I went from a gas 2014 Ram 2500 (5.7L) to a 2021 6.6L gasser. I pull a Keystone Springdale 3030BH with similiar-ish weight as yours. I am more than pleased with the towing capability of this gas motor. I would estimate we camp 10 weekends a year and none of them are flat tows, mostly within 30-50 miles from home.
The first time I towed with my truck last year was 120 miles one way with some good mountain roads, twists, and then more mountain. I was smiling the whole way, I never felt that I needed more power. I was considering diesel as well mostly due to availability at the time but I am more than satisfied with the gas motor and the extra money in my pocket.