How do I do this???

[CRXican]

I lack skills but might have the tools. I must have my sub (just one JL 12W6v2) mounted like so:

http://img.photobucket.com/albums/v43/eckoplaya/DSC_9068.jpg

[mazdakid]

build a box and face them up?

[baseballer1100]

Or you could fiberglass into the wheel well.

[Louisiana_CRX]

With a single JL 12...fiberglassing the rear wheel tub is your best bet....