Connecting two stereo bank batteries

So I now have 2 31's for the stereo side of things, one located on the port side rear seat (03 SAN) and I am relocating the other one to the bow under the cushion. What awg should I use to connect these? Will 4 gauge work? Is that too long of a run to not expect some voltage drop? Im guessing its about 8-10 feet....

I would want them as close as possible.. Starter and house can be apart but 2 on the same bank should have little to no resistance between them.

If you have no choice it would have to be 0 guage for that length of a run.