Peter, Ed,
The idea is to build a J-shaped (L-shaped?), unfolded bass horn with the mouth against the floor, and place the HF section on top of that. The woofer would fire downward, its back air chamber would be between the HF section and the bass horn. I'd hope to make the footprint about 2' x 2' and have the left and right sides parallel. I'd try to vary the front and rear to achieve expansion. Since it would be tall, stability will have to be addressed.
The killer for this whole project might be cost. If I can buy La Scalas for the same price, why bother? Even Cornwalls on stands would perform the way I want.
John