^ ^ ^ bada$$ is right
Well best of luck with the project, I hope it's exactly what you want and more.
Also, regarding this exercise, and knowing full well your astute observations, measuring chops, and best of all the willingness to document and share your findings here, ... will benefit the community in a big way. This will be very, very cool for sure.
I'm guessing it's been brought up already, but considering the size of the gen 2 vented cabs, I'm curious what impact, ... if any, you might encounter as a by product of the huge physical elements being up in the front of the room (additional acoustic interactions, SBIR/diffraction, etc). A bit down on the order of importance, but if consistent with experimentation performed in my room, ultimately the playback may benefit from some additional considerations.
I followed the development thread, much good discussion there. I did follow, but as I've got nothing to offer wrt resonant systems, I kept quiet and paid attention. Your idea to adjust vent length via driver openings will be pretty neat. Good luck on the tune.
Curious, somewhat OT, but certainly could tie into integrating these monsters once their built. Have you given any thought to employing a screen-wall or baffle-wall? As I'm sure you realize the wave-launch benefits are significant, as are the many positive by-products. You're to a evolution and development point in your system whereby much of the low hanging fruit may have been picked clean, and further tangible performance advantages become tougher and tougher.
Baffle-walls/screen-walls, they're certainly not for everyone or every room. You're really locked down wrt other room considerations. Also, they really magnify the rear wall acoustic needs and importance as well. It's just a thought, you've got a lot going on already, thought I'd throw it out there.
Anyway, good luck, and thanks for sharing all the details. I plan on watching this one closely.