Dave,
Once I get some measurements done in the room, I have a 3D model in CARACAD 2.2 if it still works. It is a raytracing acoustics model that has done well in the past for my room setup. You have to create all the room materials, so it takes awhile to setup.
I have a problem installing stuff. The middle ear is not great with heights or looking up. Since the ceiling is 10ft high, probably not a good thing for me to try.
To get to this point has pretty much drained the audio budget for a long while. I still have the diffusion foam panels Igor made for me, so will start there. They survived the water problem and also have more in storage.
I do have some RPG foam panels that were not in the room, so those can be first reflection point absorption. Your corner trap design is something I can do, so that will be something to try if a friend can help with install. Or get the ones you recommend.
Until then, I have an echo chamber to play with!