Have you considered sourcing and installing speed bleeders?
Introduction - Speed Bleeders - Russell Performance Products
You basically crack open the valves and they act like check valves, no back flow.
Fill master, keep an eye on it and pump several times. I used to do the 2 backs then the 2 fronts on my RX7 with these. They worked great and saved a lot of time.
Also, once you have the brakes bled and sorted and you still have back brake lock up, can you change the bias? If not, then consider modifying the rear pads so they are smaller and bite less.