GPS Wiring question.

I just bought a Magellan RoadMate 1700 GPS, the one with the 7 inch screen. Since I have a rear view monitor mounted next to the instrument clusteron the dash, I thought I might mount the GPS up in the center top of the windshield that is blocked off for the review mirror. My question is, do you think I can tap into the Cabin light to get my 12 volts? The unit needs 720 mah to operate.
As always thanks in advance,
John

Cabin Light wiring is not strong enough as to fusing.
I'd drop a mouse back through to to your cig lighter splice positive wire and rejoin;earth off the neutral on the ground of the sprinters lighter.
Richard