Its ok, and probablly will help a cape relax and stretch more. Dont go over 90deg, and 1/4lb salt to the bath. If it is tanned correctly, you can go way hotter than that, but there is no need to. REMEMBER, a skin can only take hotter water temps, IF TANNED CORRECTLY, and then it depends on the tan used, to judge the heat it can handle.
EVERY SINGLE THING TO DO WITH PREPPING A SKIN FOR MOUNTING, works better with warm water. Weather it be rehydrating, pickling, degreasing, tanning, or neutralising.
That is good to know shaver I might just venture out and try it got three to do this week