@dvn4life1972
I averaged about 13.5 mpg on my recent trip, keeping the truck around 70mph on the interstate. I usually run my Toyo AT2s at 40psi for road trips, and my typical tactic here in S. Idaho is to find a semi going around 70mph and cruise control behind them. I'm not sure how much that helps at safe following distances but it's worth noting.
I've decided I'd like to supercharge the truck by adding the factory supercharger from a Camaro ZL1 - I don't expect this to impact fuel economy too much but it would make merging into traffic safer, since I've found that there's not a lot of margin with the stock setup. I may try just adding a cam and some other inexpensive modifications first but the idea of a supercharged Suburban appeals to me.