I put a stainless eye bolt thorough the passenger wooden floor. The a stainless cable with soft eyes to go through the case handles.
A word of warning though , if your dealer screws back on the ali plate for the battery & replaces one screw with a long one it can make the plate live if it pierces the high power cable. If your eye bolt touches the chassis cross member and the wire gets close to the plate the car catches fire.
My conclusion is therefore to do this on the drivers side.
