I thought about having a "dumb side" for more air space but really like having the floor open, you can put a lot of stuff right there with the seat up.
I basically want this.... but for a KC
http://www.jlaudio.com/stealthbox/titan.html#
For some reason they decided to only make it for the crew. I'm sure it was easier with the larger area to work with but it shouldnt be that much different. They made that one work with 2- 10" w3 subs. They should be able to make it fit just one 10 or even a 12 in a KC.