Thanks for the quick response. Let me clarify.
I can put it anywhere along the front wall, giving me plenty of options for placement. From what I understand this is where most would place their subs and where I've always gotten the best results in the past.
What I don't have a clue on is whether the height of the placement is going to have a similar impact to the lateral movement along the wall. Typically, the logical placement is on the floor, although I've heard of installs where they have added downfiring subs in the ceiling (different from this again).
With the PC12-NSD having ports on top, this puts the sub about a foot away from the ceiling. I suspect most of the sound is going to be reflected because of this. Is this placement a bad idea for this particular product.
My next option is to buy the PB-1000 ported 10' sub and move the wall back 2 inches in that part of the bookcase so that it has the clearance. Again, I can place it anywhere along the wall (minus the exact center), I just don't have the depth to fit it on the bottom shelf. This wouldn't be the funnest of the projects, although possible if necessary.