GP wagon was very much standard - it lased well into WW1 and probably had its roots in Napoleonic times.
Ox wagon was also standard - but many Boer wagons of the period were more of less similar. We can speculate that many ex-army wagons were sold to the private owners (Boers or Rhodesians) as a surplus.
I am great advocate of ox wagon as I can not imagine African warfare without them!
Just little conversion and you can make entire lager!