Sorry Jungalbutt, but it looks like your thread is getting jacked, (that's odd...I don't recall THAT ever happening before... ) since your original question was answered, I hope you don't mind.
Most here, who use a full size spare, carry it on a roof rack. Kenny has his laying flat in the cargo area, with a contoured box fabbed up around it that looks pretty slick.
I don't know what the biggest tire you could fit in the door is, but doubt it would be much bigger than the stock mini doughnut.
When the spare is moved elsewhere, you can fit all manner of seldom used stuff back there...12-volt air compressor, jumper cables, off road creeper (drop cloth), MRE's, xtra parts, antifreeze...what ever your imagination & space will allow.