Anyone carry a "temporary use spare" in their car?

So if I have a sure grip with 28s in the rear and 26.5s in the front and the spare will only accomodate a 26.5 ( I think) Im SOL if I get a rear flat.....sonofa.........hmmmmm... what type of solutions are there???!!! Maybe a trick air can tucked away in the quarter and a plug kit in the glove .