You'd have to put the mismatched tires on the front and free wheel them so they have no affect on the diff. The problem is that the two sides will rotate at different speeds and wreak havoc on the diff/axles. You'd not be able to run them on the rear like that, so you'll have to swap 33 to back and spare to front if flat is on the rear.

That being said, steering will not be fun on the way home if you had to go very far. Offroader has a good spare 33 that I was going to buy, but now cannot. Talk to him as it was a great deal!

All of this info is as I understand it (I'm in the same situation, btw) and someone else will chime in if I'm on crack.

HTH