[Tommy]

Based on an online voltage drop calculator, and an assumed 300 amp draw from your starter, size 0 cable would yield about a half volt drop along the length of the cable. Smaller size 2 cable would increase the drop to more than three volts. .. I mounted my battery in the trunk and found the most affordable cable in size 0 was welding cable. I don't see why any well insulated cable of sufficient size with enough flexibility to be routed the way you want to do it would not work.