Um, once or twice a month for 6 months is double what I do. I love my 3/4 ton GM 6.0L/6-spd combo. Compared to my 2003 F-150, it not only is far more capable and handles any trailer much better, it also is significantly more powerful AND uses less fuel! You'll probably experience the same if you went to a newer 3/4 ton gasser.
Will a 2009+ GM half ton be an improvement? Yes. Will a 2007.5+ GM 3/4 ton be better? Yep.
Skipping the half ton save you a lot of work trying to find out if the newer used truck has the proper equipment, HD towing package, 3.42 gears. All 3/4 tons come with that. Plus, what many people recommend anyway like LT tires, integrated brake controller, etc.