clutch heat issues

On the B8 (and B6/B7) the clutch fluid is shared with the brake fluid, via a slave cylinder. My ridiculously over specified Brembo brakes can handle the heat just fine. My clutch system cannot and if I’m too busy with the gears at the track, I get bad clutch slipping.

What happens is about 10 minutes into a session, the clutch pedal doesn’t come all of the way back up on every shift. It will sort of stick half way down. To avoid it, I’m shifting less. I’m making sure I slightly over-rev (instead of under-rev) the downshifts. I let the clutch out more slowly and deliberately, also known as grannie shifting.

What are my options for fixing this? Can I have two master cylinders and separate the systems? Should I go back to JHM and switch from the stage 3 organic/metal hybrid disc to the stage 4 kevlar/kelvar disc?