Inspired by your loader
Ah! Yes, that's the way to do it; there are a lot of assumptions and copying that went into optiLoader that have proven less than wonderful since it was first written.
It might need a bit of peer review before it gets released onto the world.
It looks nice. How come the signature table includes a bunch of devices that it doesn't actually know how to program?
Are you going to include the host-side program to produce C data structures from .hex files?