Jeremy,
Your information on A/C refrigerant is not correct. New R-22 systems can not be manufactured after 1/1/2010, but it will be available to service existing systems until 2020, and after that it will have to be recycled to service existing systems. So there is no worry about the availability of R-22 for years.
There is also a concern with R-410A because it has been shown to cause global warming just like R-22 if you subscribe to that theory, but it does not cause ozone depletion, so it has been approved as a R-22 substitute.
R-410A also has higher operating system pressures than R-22, so it is more difficult to design a motorhome system that will not leak because of the vibration in a motorhome with the higher pressures. The early R-410A systems also had higher compressor failures because of the higher operating pressures, but I think that the problem has been corrected.
Also the diagnosis that you got on your SCS unit is hard to understand how a qualified A/C technician could come to that reasoning and harder to believe since you said that your compressors were running and they could not run without refrigerant.
Gerald