Mr Clark,
I can say definitively that all survivors on both C/HH-3E's and HH-53C's would have been hoisted from the right front door, since that's where the hoist is located. There were operations where we employed from Jolly's via fast rope, rope ladder or rappel from the rear ramp, and we even do so today from Pave Pigs (MH-53). We also do most drops and RAMZ (Rigging Alternate Method Zodiak) from the rear ramp. Of course if there's an LZ nearby and it would limit our exposure to ground fire, we'd prefer to get the survivor packaged up and then have the Helo plop down and take the PJ/survivor onboard.
Down at OLH (PJ school house in Kirtland AFB) we never trained for any hoist Op from the rear, and I've never seen a hoist mounted there operationally.
Hope that helps.