Speakers in the Back of Hertz Hall

There are just a couple of things you need to meet in terms of public safety:

1). tape down any cable that crosses public pathways (including aisle stairs and in between row of seats)
2). at doors, run cable over the frame, not through the floor.

Assuming you are running the cable from the mixer (located somewhere center in the house), you have a couple choices on your cable route:

Choice 1, run cables under the row of seats all the way to the wall (east or west, cut across the aisle at bottom of step, tape this portion down), go up alongside the wall (tape cable down once on a while), then cut across the aisle again before the wheelchair platform. Go under seats and cut through to back wall at center end of wheelchair platform.
Choice 2, run cable straight back from mixer position. If you don't want to tape down every section of the cable that goes from row to row just block off the middle seats of every row.

There must be space for wheelchairs at the house rear platforms, so the only space for placing speakers would be in the inner part of it.

Easiest way to get AC to speakers in the back of the hall is to run an extension cord up from the AC outlet at the very back of the hall, behind the seats. Run the extension cord(s) behind the last row of seats to house L and house R speaker positions.