That would bring serious implications as far as duty periods and rest. That said, I have my A&P and would not undercut other mechanics by performing work for a regional while piloting for them.

The standard call out fee would be a minimum of 4 hours of pay at an overtime rate on a base rate of $106/hr (the shop rate at the last repair station I worked at.) That's $636 just for the first 4 hours. I bet they would try to just pay a regional pilot straight time at their normal rate.

This should be a flat no from any pilot that is a mechanic as we do not need to start putting mechanics out of a job by undercutting them.