I have heard people say that this technique is documented in some Mercedes
workshop manual. I dunno. It should work just fine as long as you can get a
good seal on the hose between bleeders and keep the bleeders from leaking
around the threads. Unfortunately, this is easier said than done, especially
since you say that "the bleed valve is hard to get a drain hose on".
The Gunson Ezi-bleed makes this job extremely simple and easy with no risk
of running out of fluid unexpectedly, plus it allows you to simultaneously
flush the entire fluid system. That is what I used a few months ago when my
clutch master went out on me. Alternatively, the setup here:
would also do admirably.
1972 Midget with Datsun 210 5-speed