A marriage ceremony can take place almost anywhere, as long as the legal part of the ceremony is conducted or repeated in a church or other building used for religious services or in a public office (i.e. a Government office) or in a private dwelling house.
Basically, as long as the signing of the register/marriage certificate is done indoors.
Your Marriage Officer will be able to advise you of the best way of combining the legal requirements with the particular venue you have in mind.
Legal Requirements for Weddings in South Africa
Legal FAQ’s for Weddings in South Africa
Marriage and South African Law
Same-Sex Marriages in South Africa
To Take His Name or Not to Take His Name