You are a man possessed and an example to all of us to follow in the wake of your 'mod madness'!!! :notworth:
(I'm doing a GPS thing also, more to follow....)
Not "madness" exactly-- just very, very detail oriented with my toys.
I *think* my GPS solution (after a LOT of research) is to use an Add-a-Circuit wired into a special USB port that has essentially NO draw when quiescent. I think having a regular USB hardwired to the battery is what contributed to my original battery issues-- even unplugged, it was drawing around 0.035A. The new one I got won't power an iPad (not that I care), but will power a GPS or cell phone fine-- and draws only 0.002A when it's unplugged. From there, I have a another magic cable that will go from the USB port to a micro USB to power my GPS.
Go to 3BRPowersports.com for more information.
For the GPS, I'm going to use the Garmin NĂĽvi 3597 LMTHD that I have in my truck with a Ram Mount Tough-Claw handlebar mount w/ double socket arm & Medium-Wide Aqua Box-- that should make it waterproof and easily removable from the bike at the end of the day. The Tough-Claw is pretty slick and will mount up very solidly to the bars-- the double socket arm will allow me to get the GPS mostly behind my windshield for additional protection.
That's the best solution I've been able to figure out. I'm still waiting to hear from Bogie in the UK if he came up with a switched power source under the seat, but I don't think the plug he intends to use will work. He thinks it's switched, I think it's hot. I'm hoping he's right, since that would be a more elegant solution.
But, I'm holding off on the wiring until I see his results.
R.