Sub Box Question

[viking]

KRAK,
I was in your position a few years ago. Found that with removal of the steering column I could build a box for my 12" JL W3 with about that dimension. It was a tight fit but I got it sqeezed in on top of the foot rest.
Some pics in my profile. I can snap some more if need be. Haven't had a whole lot of time to be on here much so be patient with me

[ian ashton]

All that assumes you don't have a heater...