I have a couple of observations/questions if you don't mind.
This looks more like a U-Frame with 1 side tapered, longer D and turned around backwards than the Nelson Pass's SLOB project (e.g. no large front L/R baffle, different single driver orientation, no force cancellation).
A U-Frame has a cardioid response on the driver side. The OB/dipole cancellation happens at the back port.
Since the U-Frame is turned around backwards, the cardioid response would appear to be firing backwards towards the front wall, not towards the listener.
The cancellation at the Maggie interface may reduce any force on the Maggies.
Can you describe why it is NOT a tapered U-Frame and why it is a SLOB ?
Also, can you please clarify if and specifically what parts Nelson Pass has designed on this project ? There appears to be some question/confusion on the web if he was directly involved in designing it or not or if it was inspired by one or more of his other projects (e.g. your plexiglass speaker clone).
https://www.stereophile.com/content/gramophone-dreams-26-nelson-pass-harmonic-distortion-page-2Thanks much.