We use a GPS unit at work and it runs off a 12v battery. It really is a pain to take it and charge it all the time. So I decided to set up a solar panel to charge it. I used a basic charge controller and reclaimed a coil from a heater that I am using for the dump load. The panel is a 20w and seems to be working great.
Good job, just hope you don't get a meltdown come mid-summer ... Looks like the perfect application for an affordable size panel too.
