I doubt this will remain a mystery, given the collective knowledge of this group.
I've attached a couple of screen shots, one a 300 minute sub and the other a 420 minute sub. Both were taken last night at Highland Glen Conservation Area on the southern shore of Lake Huron (Bortle 3) at around 3AM.
The exact same equipment was used: Redcat51 with ASI183MM Pro and Zwo filter wheel, using Optolong 7nm Ha filter. Subs of the exact same length were also taken using Optolong's Pro filter. They show much less pronounced flare, suggesting that the flare light source was mostly around the red side of the spectrum.
The rig was located about 2 meters from another one with an Orion ED80T CF on it. I was using a red head lamp (generally pointed directly downward as I moved about). The nearest city was Sarnia - Port Huron, about 30km's to the west. Needless to say, the scope was pretty much pointing straight up though, and the area was surrounded by very tall trees, about 25 meters away on the west side.
Oh, and it is possible (although I am not with the equipment to check at this time) that there might also have been an additional filter screwed into the RedCat's filter chamber (with possible candidates being IR-Cut or UHC).
So, what do you think I did wrong here?