Well the solution wouldve been leaving the battery where it belongs. I dont see it as being safer when in the passenger compartment or trunk. Atleast under the hood the hood and firewall block it. In the trunk just the lid and a seat or piece of tin blocks it.
Ive seen alot of switches mounted near or thru the license plate. Probably the best bet if you really need it in the trunk and plan to hit the track.
Mine is staying where it belongs.