Hi there!
Hope I'm not too late on a response...better late than never though. We did a trip through Zimbabwe to Botswana and we didn't have any problems with regards to our licence. Both my partner and I have Bike Learners and we have never been asked to show our drivers in any other country other than SA...THEY WILL however ask to see your import permits for the bikes.
She'll be fine...tell her she'll get lots of admirers

on the way...I know I enjoyed the attention

!
I hope this info was helpful...let me know if you'd like more info!
Ciao!!!