I can carry a 33x9.50 (new) MT underneath, or I can put it inside, strapped to the roll bar. I do plan to go back to a rear tire carrier, though, since a 35x12.50 is just too big for inside or underneath.

One other option is one of the 34x9.50 Swampers on a skinny rim for a spare. They run tall and aired down might fit underneath. Only drawback if you run radials is that they are a bias ply tire, so might be a bit funky on the road.