Rather than trying to fix a puncture after it has happened to the rear tyre (not an easy task in that position) a better idea is to prevent the puncture in the first place by using a puncture preventative such as OKO, Puncture Safe or Auto Seal. Apart from the difficulty of repairing, a rear wheel puncture it is not something you want to happen from a loss of control perspective either. The other bonus is you don't need to carry the repair kit.
