This is a great Q&A. It is fun to think about all this, and I have learned a lot by reading the various ideas here.
So let me toss in my 2 cents worth, speaking as a former Commo who had to deal with Doppler on a routine basis.
Instead of predictive modeling we simply went out and figured out what worked.
Back at Fort Richardson we would track a few of the Oscars with hand-held Alaskan Arrow antennas. (They can not only be aimed but also rotated to peak the signal based on polarization) Whether at the Center or out in the field, the procedures were the same.
This was grunt-work field comms.
It all had to fit in a backpack and be ready for use in minutes. Our "2" man would give us the pass predictions for the day.
Our mantra was MIW - Make It Work.
So we would use CHIRP to pre-program the Yaesu VX-8DR radios with three NFM channel pairs for each bird. The Alaskan Arrow has a diplexer (their word) so one radio can work both VHF and UHF alternately.
AOS: 5 KHz Above Center - for when it pops up moving towards us
CTR: Center Frequency (145.800 simplex for the ISS, for instance)
LOS: 5 KHz Below Center - for when it is moving away ready to vanish
It was important for the radio man to have a quick way to simply rotate the channel selector to track the Doppler shift for the very few minutes we would get at 61 Degrees latitude.
Sometimes I would do it all alone, handling the radio in one hand and the antenna in the other.
At our latitude it was important to use the full-length Alaska Arrow to get the most gain so I mounted mine to a microphone stand.
Our comm windows were short. But we Made It Work.
So, even though there was not a lot of math involved at the level I see here in this Q&A, this was the end result - it worked reliably.
We could talk to our own field units and sometime even reach California ham operators.
Adjusting for Doppler was not optional in the least. Very important part of the setup.
To get Full Duplex, it is definitely a two-man job. Two radios and a hand-held antenna. The Alaskan Arrow allows you to bypass the diplexer and simply connect the UHF radio to one set of elements and the VHF radio to the other.
Of course, Full-Dup has not been supported by ARISS for voice, in my experience. It is usually just VHF-Simplex.
We always just listened for them. Too much QRM for us to try to compete.
For all the birds it is not polite to try to overpower others so we stayed strictly at 5 Watts output (with high-gain antennas). We found that in general hams are usually polite on OSCARs. Most QRM is accidental.
Now that I live Outside, in the contiguous states, the comm windows would be longer, so perhaps I would use 5 channels with 5 KHz spacing.