[Pete]

If you want the maximum safety with a total system cut off switch, it should be mounted as close to the battery as possible and in the GROUND strap.
NEVER IN THE HOT LEAD.
With other systems the main cable is left hot with the switch off.

There are several other manufacturers of heavy duty switches similar to the Cole Hersee one. They can be mounted in the center cross member just ahead of the driver seat with the shaft up through the floor for easy access.
Done right the floor mat will cover the handle yet it will still be easy to access.