Sounds great. Not too different from my setup except that I am using 35W or 35W equivalent lights. My box is Carlon 6x6x4 electrical box on one bike, and I am getting a Pelican waterproof case for the other bike so I can use a larger battery which is currently in a bar bag. I am using SLA batteries so I don't have to be concerned about which side is up. Do you know the brand name of the light you are using? Does it take MR16 bulbs (about 2 inches in diameter) or is it more like a sealed beam headlight?
Regards,
Raymond