If you don't have at least 500 hours or already have a CAAB CPL then you going to struggle. You can only 'validate' your current licence until you have 500 hours flying in Botswana. Only then can you actually get a conversion to a Botswana licence. This was mentioned on another forum and confirmed by a mate of mine who is working there to be something to that effect. Anybody else confirm?
Personally, I think you are wasting your time. It's becoming almost impossible to break into the Southern African regions: Botswana, Namibia, South Africa etc etc. Hell there's even a surplus of pilots in the DRC looking for work! Not to mention Tanzania...need I carry on?
Good luck! After all you never know and it does change almost daily!