I still am suggesting to not to mess about the wiring yourself and let some experienced electrician help you. Cuore Wiring is Easy Point to point Joints and connections but still experience is advised. The better thing is to sort your OEM Wiring rather than changing the whole setup!
Here is Pakistan you will find wire strength calculated in "mm" (millimeter) where as in America they use AWG (american wiring guage).

Usual connection here are done with 4mm-6mm thick wire, with thicker wires for ground, battery and generator connection, starter motor etc and 10-12mm (0 AWG). but the "Electirician" should better understand. there should not be any short cuts and breakages and joints in between connection and every damn thing must have a fuse from the fuse box no direct setup and with experience i am saying a "Battery Cutoff Switch". Installed it in my Lancer after restoration and installed it in my Khyber too.
actually i wanted to install complete AC system in my Lancer it is one of the few things remaining that is why collecting info of the best AC guys. Your costs are very reasonable!