I don't understand some of those restrictions, and I am sure you do not either. Propylene glycol is used in medicines, foods and cosmetics. It is also used by some dairy farmers and might be available from a supplier of such things. If you can get glycerine, it will do as well but is quite viscous.
Are you using shutter speeds to set the exposures for the various zones? If so, it might be a good idea to test the shutter for accuracy at the slower speeds. Of course, if that is the problem, it should show with other developers as well.