The PL tone suggestion just needs to be tested to get
a realist feel on what to expect. We have had issues in the past, with putting stuff in space that was not properly tested end to end.
You can't do a real test until something in orbit sends a PL tone ... but theres another, related, effect which someone might be able to check. On a spaceborne 9k6 packet signal someone could observe the extracted 9k6 clock signals and see what happens to them; there will be a doppler-related drift in the clock frequency. Certainly when I was QRV on 9k6 pacsats I saw this (albeit small) effect.
Packet is affected by Doppler when it begins to get
above 2.0 kHz. The amount of error is also dependent on the Signal level at the receiver.
The issue here is received signal distortion caused by being off-tune. It is not the same effect as doppler
73 Richard G3RWL