Nice build, have something similar to yours but different as well, mine is a 2000 with a 3.0 flex and 8.8 &373 gears.i definitely agree with the added cooler as I run 200 degrees on the highway at 70-75 mph loaded of coarse.i am running same tire size as u and will say a 331250 will fit on stock wheels ,don't look pretty but I got around amazingly well with them.have you looked into a roof rack for the cab ?
I gotta say your rig is almost exactly what I'm looking to build I have had 2 rangers in the past and loved them both. Just sold my F250 crew cab realized it was just too big for what I want so I'm looking for another ranger again. Nice job on the truck.