Take a look for yourself!

If I had this to do over again (and I will), I would move the sub very close to the rear seat, as this would allow you to not have a raised platform to set it on.  Right now, the rear of the carpeted plywood platform has a 1"x1" riser to make it level.  By move the sub back, the platform would be smaller, and not require such a large spacer underneath.

The reason for all this is that the seat is somewhat difficult to fold forward, as the center of the cushion hits the platform before it is fully vertical.