Moving to Joburg - Freelance visa? (Johannesburg)

Hi! My husband has just been transferred to Joburg for 3 years (due to start in December) and his company is providing him with a work permit etc.
However, I can't get any answers about what I need... I work as a freelance translator/ proofreader. My client base is all online (in Europe), and I can take that work with me anywhere.
But I can't find information on what kind of visa I need to work as a freelancer. My languages fall under the 'critical skills' list (French, German, Spanish), but I wouldn't be looking for permanent employment which is one of the conditions of that visa. I would never satisfy the monetary conditions of the 'own business' visa, so that's out.
Are there are any other requirements - pension payments, health insurance if I want to set myself up as a freelancer?
Sorry for the long post - Any tips greatly appreciated!!!