Theory is all very well but what about in practice:
Just tried my Yaesu portable in 8.33kHz mode and can clearly pick up 118.800 and 119.100 on 118.805 and 119.105 respectively, although I noticed that a higher signal level is required to open the squelch on 118.800.
Obviously, I did not transmit but have previously picked up 120.605 transmissions with my 25kHz radio in the aeroplane set to 120.600 so hopefully, a 25kHz ground station would be able to pick up my transmissions on the nearest 8.33 kHz frequency. I will try that the next time I fly,