Heavely modified Pensil P70, or how to do a ML-TQWT for the CHP-70

[Squeak]

I want to build a simple transmission line, like the Pensils for the CHP-70.
I have some special requirements and questions though:

- I want the cross-section to be square, not a rectangle like the Pensil. I know it's rectangular to minimise standing waves, but seeing as the microtowers gets on fine with a rectangular crossection I figure with the right stuffing there should be no problem?
The square looks equally small from all sides, is easy to position right and has better balance.

- I want the driver hight to be 105 cm, which is exact sitting ear-hight for the people it's intended for, to make the most of the dispersion pattern. So we are talking 115 cm outside hight.
What does that mean for the rest of the speaker? Should it be slimmer, or fatter with a different tuning? Could I subtract enough space by putting in a slanted board at the bottom, reflector style? Or would a slanted wall destroy the wanted resonance?
I could also just raise the whole speaker and put a reflector under a down firing port like the half Chili Chang.

- You don't hear much about the ML-TQWT approach for the MA drivers. Are they unsuited for the loading method with their higher Qts? The frugal horn Mk3 seems like an instance of a TQWT though, with the port a little larger than usual.
It would seem ideal to have quarter wave tuning in a cab where the speaker is at the very top.
Seeing as it's so very easy to do building wise (only a slanted board), this must be a for a reason, right?