man no wonder you don't get any sleep at night.
your question has already been answered: 11 mins is the ABSOLUTE maximum, if you were sampling records you could squeeze out a little more by sampling on 45, but for your live stuff you cant.
If you really want to use the mpc for this you need to record shorter bits of your jams(2-4mins?),extract the best bits to new samples, save both new and old samples to your hard disk or compact flash.
At this point delete the big samples from the ram, you will be left with the choice bits of your jam. drop them into a sequence and repeat this process if you want by recording more on top or whatever.
It does sound like you'd be better off with a portable multitrack or a laptop and sound card for recording long pieces like that.You could record multiple instruments to multiple tracks for starters.
The mpc's audio tracks are more suited for recording a few short ideas than for recording a jazz odyssey.