The type of driving you do, meaning mostly highway, would be very conducive to a big diesel. That said I don't think you need one for your trailer.
I would look into a max tow/payload F150 with an Ecoboost, or if you can afford it or just plain want more truck, look at an HD diesel. The Duramax would be my pick of the newest models, or a 2018 Ram CTD. If you want to change, anyway. It sounds like your Tahoe is meeting your needs adequately so the other option would be to stick with it. Maybe beef up the tires some because that's probably the weak link.