What is around the outside of the battery box in a mcs, and can i drill holes in it?

I got my methanol setup friday and will be installing it this week some time. I am planning everything out and am pretty much set on installing the pump in the boot. My first thought was to build a box to install in place of the battery that would have everything in it(ie odyssey, pump and reservoir). But the battery box is so small I am now thinking of just installing the pump and reservoir right to the wall of the battery box. I just dont want to drill into something.

 

The battery box itself is steel sheet metal. Surrounding it on the sides is a layered aluminum heat shield, and the bottom has a sheet aluminum shield/skid plate. Surrounding all of this is the exhaust system. The aluminum bits are bolted to the box and can be removed, as well as tweaked slightly to provide clearance for items that you are planning on passing through the walls of the battery box.. To gain extra clearance for umps and reserviors in the battery box itself, you can fit a lightweight, smaller-sized battery.

If you dont have xenon headlights in your car, you can purchase and adapt the headlight washer fluid tank that fits inside the left side fender.