It's fine. If it can keep the spare tire/jack from moving around under hard cornering, a battery will be no problem. Just be careful not to drill through the box underneath. I forget what it is/does, but it's something to do with the fuel system.
2000 Contour SE 2.5L ATX - Toreador Red
2001 VW Golf GLS 2.0L MTX - Tornado Red
Buy my possessed VCR!!