Did anybody else catch that he said his current box doesn't have a bottom?!?
Umm, in my opinion this is just a bad idea...if there is any air leak at the bottom (which, well, there is) you're not getting the compression in the box you need to create worth while sound (and you're probably making the suspension take a bit of a beating if you're putting too much power to them).
IB (infinite baffle) setups like you're proposing are possible, but don't rush into it. You get increased efficiency with it, and increased thermal power handling, but the mechanical power handling goes way down because you effectivly have "no" box.
Also, to make it work properly, you should completely seal off the front wave from the back wave of the driver, i.e. completely seal the opening.
If you see him around (not sure if he's even been on lately) talk to jmac...also, lloyd (bigbassman) knows quite a bit about them I think. I don't know for sure, but I would assume moe lester and ramos are fairly knowledgeable about the concept too (possibly even squeak and jack frost?). So, do some research, and don't rush into it. If you built a box with no bottom and didn't see a problem with it, I wouldn't do this until you've learned a lot.