Towing with a tundra in the mountains

I been pulling my wet 6800# Jayco 30' travel trailer up and down mountains with my 2012 5.7L V8 Toyota Tundra for years. I haven't had any problems and just keep my RPM's somewhere around 3000 to 4000 going up. My concern with my Tundra is never been my tow weight, which maxes out just under 10,000#. My concern has been my payload capacity, which gets eaten up by my family/tongue weight/kayaks thus can't use my bed for anything else. I love the Tundra, but wish it's payload capcity was closer to 2000#. My next truck will be a 3/4 ton or 1 ton so I can haul more gear and tow my trailer.

I get about 10 MPG while towing. Thats not too bad for a gas truck while towing in my opinion. Sure its not diesel mileage but i also didnt pay the diesel pricetag too, which I dread for future trucks. I love my tundra though.