Do you really need to have the subs on the front stage at all?

I'm kind of confused; it seems like your constraint is footprint. If that's the case, how about a SVS cylinder?

With a few, pricey exceptions, I don't think you can get the extension you want from movies from a very small enclosure.

And, fwiw, I am now convinced that towers are still pretty critical for music, but that 3 M22's plus subwoofage is the way I'll go for the next iteration of "home theater".

bibere usque ad hilaritatem