Get a Mitevac to bleed the brakes. That way you can do it with one person. If I were replacing my rear calipers, I would also replace my brake fluid at the same time. You can use the Mitevac to suck out the old fluid, then pull the reservoir off (it is just pushed into the master cylinder with rubber grommets so it pulls off with no tools) and wash all the old grunge out of it and put it back on. Now fill the fluid up to the top and bleed away. Do not touch the brake pedal while the reservoir is off.
I would also think about replacing the flexible lines that go to the calipers while I was doing the other work.
Mercedes recommends replacing the brake fluid annually, preferably in the spring.
This is my 500th post!
