Where and how to mount disconnect switch in Tudor without new holes in metal.

[M2M]

My car is 6v positive ground, and I've decided fit a disconnect switch on the cold side (the positive ground side).

First question, what size wires should I use from the battery to the switch and then to ground? 1/0 AWG (0 gauge) thick enough?

I already have these parts for the job:



I don't want to make any new holes in metal and I want the switch in easy reach inside the car so I'm thinking of installing it on the center floorboard under the front seats; although I'm unsure what the best way to do so is.

Your thoughts?