I've been following this thread and eagerly awaiting an update. I've been toying with the idea of a 12v system, and I must say, this is brilliant! Simplisity is always best.
I would recommend that you get an advance disclosure agreement. Its a document filled with the patent office for a temporary time frame. It allows you to approach manufactures with the design with out the fear that they might steal the idea.
Good luck buddy.... please keep me informed!