Yeah, I thought of doing something like mounting the sub to the "rear deck", but was wondering if the side walls were strong enough to support the weight, especially with the added strain of stops/starts/turns/bumps.
The design I was thinking about involves fabricating a new deck, and angling (actually curving) down and towards the seatbacks so the sub fires at a slight downward angle. This would help increase the distance the sound waves travel thereby allowing me to hear the longer wavelength of deeper notes. This design would also give me more floor room in the trunk. I could also make a removeable panel where the sub(s) mount so I could change it over to a dual sub setup without re-doing the whole thing.
The downside to this is that it would somewhat negate one of my goals: easy access to the spare tire. Currently, I just remove the sub box and flip up the amp rack. Removing such an integrated part wouldn't be that easy I'm thinking.
Anyway, I'm very happy with the amp rack and I already have a VERY solid, nice sounding, properly tuned sub-box to use in the interim while I go through a notebook or two of design plans. What else is there to do in the winter months - it's too cold to play with my nitro R/C and too much snow to play disc golf.