Thanks ctuna, that E91 build sheet was helpful. I've combed through so many threads but search parameters are just so generic. Looks like I'll try going over the strut tower and into the rear corner. I'm sure it'll look flush once I've reassembled the trunk.
The amp is going in the under floor bin. It's a mono amp just to drive the sub and I already hooked up the Technic harness and ran rca's and remote lead. I'm really pining for an integrated fiberglass enclosure for the sub but I'll probably try my hand at fabricating one since they seem to be going for a pretty penny (when available, that is).