Glad I stumbled upon this, because I was thinking of doing the same actually, and for the same reasons too just for cleaning up the bay a tad. Rafaelli I could be wrong here, and Scott will surely correct me if I'm wrong but I don't think you want to have a ground that long man. IIRC you shouldn't have the ground any longer than 3ft. But then again that could just be for car audio.
One question I have, on the same subject as Tony of course

What size wire should we use to do this? I personally don't think I want to buy a kit, unless the wire cost as much as the kit. So if I were to buy just the wire, and fab up a box, what size wire would i need? And what kind of wire? (Like welding cable)