I want to bolt something to the floor of the trunk. Was going to use 3/8" self tapping bolts to attach to the front portion of the trunk, but the gas tank is under it.

What is the clearance between the tank and the trunk floor? Any shield between the tank and truck?

Any better place to attach a 12" x 12" box?

OnTheRoad

 

12" x 12"... I'm guessing it's a sub?

I'd be wary of securing anything straight onto the floor of the trunk, but many others secure their subs via a piece of wood under the removeable carpet in the trunk.