oh... just re read.. your battery is on the wrong side.... that would take at least and extra 20 feet or more of wire.
can you swap it back?
we have a really clean set up.

I would not run it off the starter. I think that you would end up with a dual hot and it could cause alot of heat in the starter wire. not to metion a possible back feed to the smaller wires.

(yeh that sounds stupid but thinking of the ground loop part of it.)