I suspect that you might have some problems with this, so report back either way. I have never used hangers before so maybe I am wrong. I assume that if the film is held in place somewhat loosely on the 4 sides then it could pop out when inserted, agitated, or removed from the tray. If the film is held tightly by the frame, then it will probably bow and maybe pop out if not careful.
Originally Posted by CuS
The manufactured sloshers have holes under the film to allow free flow of solutions when raising or rocking the trays and that promotes even development.
Also, one benefit of a slosher is that you can process each sheet for a different time which would be impossible here.