Someone had to ask... haha

I'm working on the design for my custom sub enclosure / amp rack which will likely take up the ENTIRE rear door. I'm trying to stuff two 12 inch subs and a fairly large amp in there, so every cubic inch counts. If possible I'll just work around it because I might eventually want to install a backup cam, but I'm not sure that I really need one. I'm kind of used to the blind spots.

So does anyone know what guage the battery cables are?