Greetings : )
My wife and i too went back and forth 4x4 vs AWD. But what made the difference for us was:
1) We hadn't engaged the 4x4 in
our TACO except for about 2 times in 3 years. &
2) We loved what our Volvo x70 AWD rigs did on our wet roads year round...
So we went for the AWD and we are 100% satisfied.
On mileage... well we only really had about ~400 miles total on the stock-height rig and the millage was ~17/19 highway and ~14/15 city. I would say on average, fully loaded with all our gear, and Cari's daily driver we see ~16/18 highway (~16ish towing), and about 14 average around town.
. . .But then we have a bed, bath, shower, kitchenette, and gear for two weeks of adventure behind the seats loaded and ready for adventure 24/7!
The times you know the high-top is there is when bucking a headwind! I accidentally planned a trip to Sumpter Oregon going east on hw 26 and then west down i84/Columbia Gorge. HaHa. My Bad. They don't call the Gorge Kite Boarding Capitol of the west coast for nothing!
On wheel/tire size...they are stock. We just went 10 ply and bling rims for my wife : ) But wow, do those tires make a difference over stock 6 ply P rated!
Best wishes on your adventure and possible build.
Thom