But your passport is still tainted if you use any Israeli land crossing--they see the stamp from the other country and infer you were in Israel. Unlike what we saw in the 80s in Africa--so long as "South Africa" didn't appear you were ok. The border stamps into/out of South Africa didn't cause problems. The possession of a fair quantity of supplies with packaging in English/Afrikaans didn't matter--but the first day across the border the organizer had us stop and very carefully go over everything with a sharpie looking for labels that said "product of South Africa"--those had to be totally blotted out.

And to show how stupid things were--he also had a stamp he had made up to make forged entries on our yellow books. At that time your average joe certainly did not have an up-to-date smallpox shot--but at multiple border crossings they would hit you up for a bribe if you didn't have an up-to-date smallpox shot. Hence fake them. (Even around 2000 which was the last time I had occasion to have anything added to my yellow book there still was no anti-counterfeit protection.)