This is the control that i will use in my feeder light.

http://www.ecovantageenergy.com/cata...ms/item213.htm

I have a set up very similar to yours using plastic tool box, 12v battery, solar panel, photocell (from elusivewildlife.com), and a super bright red led brake light (from autozone).
Light after testing lasts ATLEAST 45+ hours on one charge which allows for a few cloudy days.
My only concerns are weatherproofing (I rubber siliconed mine from the inside) and how to post/install it near my feeder. How do you plan on posting it?