A twisted turn on the thread: OP are you driving MT or DCT?
As an MT driver for nearly 30 years, I was recently diagnosed with a rare carcinoma. Luck would have it, part of it is in my pelvis and I managed to figure out that driving with a clutch was a major (Literal) pain in the assteroid.
Switching from MT to DCT, the car no longer hurts me.
I don't know how many others have similar back pains - and we don't even realize it, but the clutch is beating us up. Bet you 6MT guys never thought this one through!
As for the other advice, many years ago I started wearing swat/cargo pants and my wallet in the magazine pocket (thigh). This has helped tremendously. Try that first!