GAD said:
Downsides are that the coil tap switch is not useless
Do you mean the coil tap is useless due to thin sound or that the Classics aren't 4 wire PUs so not tap available?
If the former and the coil tap is useless because it is so thin sounding, them you could do a partial coil tap. Instead of bypassing one coil with a dead short, bypass it with a resistor - effectively placing a resistor in parralel with one of the coils - gives a fuller sound than a full coil tap but less than the full humbucker. You also still get some noise cancelling. A value between 1.5k to 5.6k would probably be the go. When I do this I wire a 10K pot in & twiddle it to get the result I want & then take it out of circuit & measure the resistance.
If the latter, then I don't know - you could use it as a series switch or a phase switch or a kill switch or volume/tone bypass switch etc, except wiring in hollow bodies is a pain regardless.