Sorry for my lack of specific knowledge but I can think of two styles of wagon in use by the boer (that I associate with them anyway) but I can't remember if it mattered whether it was pulled by horses or oxen. There is the one that comes up in a curve towards the back and there is a flat one with angled but almost flat sides that come off like wings. No idea of their names sorry. Which are you after?
Some creative Googling and:
Voortrekker wagon (the one that comes up at the back)

And the 'historical boer wagon'
