Happened to me for the first time about a year ago. Car was sitting a month or so. I couldn't believe it was the issue but everything else checked out. Pulled inspection cover and with petal to floor there was plenty of gap between pressure plate and disc. Took small flat blade screwdriver and loosened disc from flywheel. Didn't take much to loosen. I've had manual trans cars for 30+ years and this was the first.

Your idea will prob work also.