08 Moomba LSV sub box question

I'm trying to design a box to fit under the helm of my 08 Moomba LSV and I have limited room...

I might be able to squeeze a premade box back behind the foot rest and front storage area(short term), but in the long run I would like a custom box to fit under there...

Would this box design work? (assuming the dimensions and the volume work for the appropriate sub) any thought or suggestions?

Thanks