Basically I want to build a fiberglass enclosure to house my upcoming 13Ov2 (my e12a just died on me

)
I have a RSX and would like to use the ~2 sqft of space my spare tire takes up for an enclosure. That's the problem, I only need ~1 sqft for the sub, how should I do this?
I was contemplating making a MDF frame for the top (I will have to raise the floor to accomodate my amps) and using that to create my glass section...
This is what I have to work with:
I was thinking about creating a frame, the height of what I need the floor to be raised: (not to scale, and a crappy paint drawing

)
My question is this, how should I make the sides of the box? I was thinking of just to laydown strips between two opposing sides, with enough slack to go to the bottom of the spare tire well (to be able to secure it.. think of a bowl with a flat bottom)
will this work? is there a better way of doing this?
Thanks
Bill
p.s.
