Got lights with switch on?
The connector under the tank is a place to look,

You can put a switch on the decomp timer & it will fire the starter. I can make mine turn over & not even turn the key on. Wont start, of course, but that start switch can get knocked off & I can start mine.
Its such a low current application the switch I use is one of those tiny little things from behind a button on the front of a little dvd player. The switch itself would not even cover the nail on my pinky. Theres a hot wire running under the seat, a solo red wire, always hot. Id have to look at a wiring diagram or pull the seat, but you can figger it out if you are clever enough to do all the other stuff youve done. Or, if you cant & want to do this, holler at me, Ill see what I can do..

That relay takes the Signal from the switch & closes some contacts,, bypass it.