your making it harder than it needs to be. if i remember correctly. you can remove horn and bracket with a socket. i think it a 12 or 13 mm.
Correct.
I bought I/S horn brackets for every Standard or Tourer I've owned, fabricated some extension wires and relocated the horns. The whole thing can be put back to stock in 15min if desired...but on my current Tourer there's now a radiator pod blocking things.