Using soap when showering in the evening hasn't seemed to make much of a difference for me when hunting in Africa, since as Charles pointed out you need the wind in your face unless in a blind . But I'd try to stick to something that isn't perfumed.

FWIW though, I have found that when hunting moose here at home that I generally have better luck when I don't use soap at all for a couple of weeks, but just shower off the worst grime with plain water. So maybe this might be a good idea when sitting in an african blind, where you don't have total control of the wind direction.

Another option is to find some fresh elephant dung, lay down in it and roll around. The smell might help camouflage your own scent. I'm not sure your PH would volunteer to join you though.