I know that the traction motors on these RDC's would not be used. This was the same scenario when the MBTA used RDC's in the 80's. What would be the problem if you paired these cars with an F40 or a geep. You probably would not even require the use of HEP if the RDC's supply their own power.
You could run them on the north side to suplement the lack of cars. They would be closer to BET and the north side does not seem to have as many restrictions.