possible error in optiboot.c ... ???

oric_dan:
I see you put the mighty maniac library in the IDE folder, instead of in the sketch folder.

I tend to put "production" cores with the IDE and "development" cores under the Sketchbook.

As another aside, I'm cooking up a way to spoof avrdude so I can use it reliably for RF uploading.

Have you searched for an existing upload protocol designed for radios? For example, I worked for a company that designed an AVR upload protocol specifically for CANBUS. It was a much better solution than trying to smash one of the Atmel programming protocols onto a CANBUS connection.

While you are pursuing the subject, bear in mind that the IDE has support for "custom" upload utilities. You are not constrained to use avrdude.