I also fall into the "no spare camp. Several reasons for this:
!) My 12RX22.5 tires weights 140 lbs without a wheel and ~200 with a wheel....too much for me to comfortable deal with so I still have to call roadside assistance.
2) The aforementioned tire is almost 4 ft in diameter on over a foot wide. This requires a significant amount of storage space for something that might be used but probably will not. Plus one still needs the tools to get the wheel off the ground and the tools necessary to break the lug nuts and re-tighten....more weight and room.
3) A mounted tire is a gamble that you have in mounted on the correct wheel since the steer and drive wheels are all different you just have to get lucky with the unlucky. The tag may or may not be different but probably the same as the steer which ups' the odds a little.
4) If you don't use it it still ages so that is a consideration.
5) Since I'm going to call roadside assistance regardless if I have a spare or not (see # 1) why not just have them bring a new tire anyway. No cell coverage...doesn't change a thing but just hop in the toad and you're all set.