You're welcome!

Understood, I've still got five different size commercial plush [super dense] carpet remnants for just such occasions. Turn the big one face down and it makes a great 'towing sled' to drag big/heavy ones around.

Yes, and no. I mean you can shrink the cab's CSA and actually get a more perceived 'tightness'/'snap', but it's because there's much less bass output to balance it out even though it's tuned the same, i.e. has a higher F3, so ideally it would be corner loaded. This is the 'secret' to Pi Speaker's PiAlign, it's an old prosound design routine based on W.E.'s original reflex alignment he resurrected/claimed for his own. For low output impedance systems, the PiAlign is preferred, but for higher output impedance the original is preferred since it de facto requires a [ideally] measured Fs tuning.

Anyway, I've designed/built far more skinny 'tower'/'column' alignments [aka ML-TL, ML-TQWT, ML-horn as well as the various 'Classic' pure TLs] than deep bass capable ones for one reason or another, including Altec loaded, so very familiar with all of them.

Anyway, shrinking yours to be only big enough to mount an 811 on top reduces it to 18.75" o.d. wide x 17.25" deep o.d. or ~7.55 ft^3 net which has much less bass output and due to the smaller net Vb the vent now needs to be 5" long. It's also acoustically too high an aspect ratio, so stuffing density doubles to 0.5 lbs/ft^3 to get a similar response smoothness:

GM