Originally posted by Ben Coburn:
Something I don't understand about the standard design: Why would one want to bolt it to the chassis?

It seems to me that a foam object like this is the last thing that should be attached with bolts. I'd expect that during any sort of not completely head on impact (the only type where the mounting matters) the foam would just fail around the mounting holes, not actually compressing or dissipating much energy at all. Gluing seems much better, not much work with epoxy gives a bond much stronger than the foam itself.

I'm just curious what the reasoning behind the standard design with bolt holes is, because I don't understand it.
Of course not, that would be silly. Instead, do like others have suggested here and glue it to a plate that bolts to the chassis.