YoungCF, don't let the fact that the XF doesn't have a spare tire sway your decision to buy one. These cars are just to much fun not to have around.
If the spare tire issue is still that important to you, you could always pick up a spare out of a wrecked Mercedes SLK (same lug pattern) and throw it in the back of your new Crossfire. Heck, maybe the one out of your C200 would even fit. Do some research. Good Luck.