C-41 in the Combiplan
Just to close off this thread... I was able to successfully develop c-41 in the slow draining and filling combo plan, and the results were fine. However, I did end up creating a true darkroom environment so that I could take the lights out dip and dunk approach instead. I find it easier, actually. And the negs come out great that way.
I use the combi plan tank for the initial water presoak, and some 1.5 liter juice jugs for the other tanks. They happen to be almost identical dimensionally to the combi plan, so the rack fits well without requiring a lot more fluid to cover the film.
The juice jugs are nice for other reasons. I can cover the chemistry while the tank is not in use, so that I don't accidentally drip liquid from one tank to the other. They also pour well, so it makes chem handling easy after I finish.