I can't recommend 15x10 for a 12.50" wide tire. For a 33x12.50 or 35x12.50 tire, I would stay with a 15x8 wheel. That's the size wheel I have always run those two sizes of tires.
You'll be able to air either of those sizes down more with less worry of them unseating on an 8" wide wheel than you would with the wider 15x10 wheel. The wider the wheel, the more air pressure required to keep the tire safely seated.
And keep in mind the wider the tire, the easier a tire will hydroplane and the slower the speed it will hydroplane at. It rains enough there in MS that I wouldn't go to a 14" tire if that Jeep is not being trailered.