There is SUP in Cape Town. The best guy to get a hold of is Ivan. He lived here in Maui for years but is originally from Cape Town. He moved back to open the SUP market there. I lived in Cape Town for 9 winters and have a lot of connections there if you have any other questions about Cape Town.
Ivan is a great guy and has the only SUP business down there that i know of to date.
here is his website
http://www.coreban.comand his email address
ivan@extremesportsmovies.com
Tell him Frank From Lightning Bolt Maui put you in touch with him. Have a great trip Cape Town is a very special place.
Hope this helps
Aloha
Frank