What is a good setup for stock electrical and 3.5 cubes gross?

[Based]

Alright I have decided I will take out two of my back seats to be able to increase the depth of my box. Now I have 21.5x21.5x(unlimited depth).

I want my subs to be facing my hatch though so I'm still stuck with just two 12's because the face facing the hatch is only 21.5x21.5. I will have to mount them in the corners of the box.

 

[Based]

Ok I think what I'm gonna try to do is make my box an L shape box. It will give me about 6.5 cubes before sub and port displacement.

I'm really leaning towards the HDS312's. I can't find any box recommendations for the FU audio or XFL 12's/15's.