Take another look at the wiring harness up by the clutch. I had the exact same problem years ago. Turns out that the wires were chafed and only when I applied brake and clutch simultaneously (like when backing out of a driveway or parking space), it would short the circuit and blow the fuse. It may not be as obvious as to be seen by a casual inspection. I would get up there with a flashlight and really scour those wires.