I would look for a power wire that comes off your key switch and runs to a fuse box, buss bar, or something to feed all of your gauges and bilge pump. Does the bilge normally run with the key off? If not, I would look at wiring in a seperate circuit for it so that it will in the event you ever want to leave it beached or docked overnight. That way you could leave the bilge pump on and take the key with you. Sorry for the long post, but that is what I would look for.
jordan