i imagine with the amount of dust kicked up by tanks, riding on them in the western desert was difficult, plus they would have been very hot!
I've seen photos of German Afrika Korps riding on tanks when retreating into the mountainous areas after Alemain and the battles of the Mareth Line but the terrain looks much more rocky than dusty.
There are some figures from various DAK sets that can be adapted for tanks riding but they are not very authentic.