I agree with @NickV - With the barrier cream, you can layer it (no need to wash it off before applying another layer). Also, protect the area with silicone bandages on top of the barrier cream. The skin loves silicone and it helps heal the wound before it gets bad and keeps it protected. Most silicone bandages can be re-applied for up to 7 days unless they get soiled. In my mom's case, they get soiled with her BM, so we often change them daily. We have found an inexpensive but good brand on Amazon. Excellent price (comparatively). See attached pic.
Also, consider getting an alternating air pressure mattress if you don't already have one. It really helps tame the bedsores.