I managed to get some (small) work done on the pack today. I installed the lower wall of the repulsor pods after cutting out the spacer I had glued in place to get the angle I wanted on the outer panels. It occurs to me that cutting out and installing the lower wall and installing the outer panels afterwards would have saved some cutting and (eventually) sealing issues. Closed in the long sides of the jetpack chamber (the blocky teardrop at the bottom) and the lower wall of the "life support" area (top area between the pods) so that I could begin building up the main area which sits in the middle of everything. I cut several 2" tall sections of foam core and hot glued them around the edges of where the main deck would fit to act as a ledge for the main deck to sit on then applied the hot glue to the top of them and pressed the main deck in.
There are gaps in a few areas but I'm hoping that those can be sealed up with minimal issue
(on the right side in this picture)

Here's a pic showing some of the internal supports holding things in their proper places.

And here's the current state of the pack.

There is surprisingly little left to do on the main build portion of this:
Close in the JP chamber bottoms (this will be where the rocket nozzles get mounted)
Close in the main deck bottoms
Complete the "life support" area (where I'm planning to attach hoses running from helmet)
Build the raised center that runs from the JP chamber to the "life support"
Close in the top and back of the repulsor pods (direction references are "as worn")
Tape, Bondo, Sand like crazy
Then I can start worrying about things like "What kind of nozzles do I want, and where will I get them?", "How am I supposed to make these pods look like they're repulsor pods?", "is this enough greeblies?", and lastly "How am I going to mount this monstrosity on my armor?"
Also... This thing needs a name. I was considering 'Basilisk' in homage to the war droids but that seems a bit much. Names are hard. Comments and advice are, as always, welcome. Thanks for looking.