I begin by admitting that I have been out of the darkroom for almost two decades now. So take anything I say with a grain of salt. Back in the 1970's, I began having problems with the emulsion softening and lifting off the paper base. My Kodak tech rep. stopped by one day and told me that the chemical make-up of the water could make such a problem. Particularly very "soft" water. Turns out, the building did have a water softener. (Eventually, we installed by-pass plumbing around the softener to our print wash area). He suggested tossing a "hand full" of epsom salts into the wash water. I still have prints from back then. The epsom salts did no harm and did keep the emulsion on the paper while wet. So, if you want to try overnight soaks -- maybe try some epsom salts-----worthy of a try???