I think that instead of converting Fordham and BPB-Lehman College into express stops, the TA can just add a switches on from the downtown track to the express track north of the station, as they don't exist. The current layout requires the train to leave the station before switching tracks, which makes it a logistics nightmare for signal operators. Then have the rush-hour locals terminate at Burnside Av, and continue to Woodlawn. Make it similar to the / on the Pelham Line. It would alleviate the capacity problems that exist at Woodlawn. The biggest problem I find with the was how crowded it got during rush hour for Bronx Riders when it reached 161st St. The only downside are for riders that only ride along Jerome and have to switch between trains on Burnside. So the would be Woodlawn, Mosholu, BPB, Kingsbridge, Fordham, 183 St, Burnside, 149 St, 125th. The would be Burnside, 176 St, Mt Eden, 170 St, 167 St, 161 St, 149 St, 138 St, 125 St.
I agree that converting Fordham to an express stop would be a nightmare considering how close the buildings are to the elevated structure in the area.