Played this again today. First game I made a mistake that allowed the enemy a 1 in 6 chance of killing off my main stack - and he rolled the six...
Second game the Allies could not take Tobruck and the Axis would not be able to get off the map. We both realized that it was not only possible but pretty much required to put a line of troops across the desert and neither side would then be able to advance past it. They could attack and maybe eventually attrit the other side but there was no way to break the line and surround the enemy. So sadly this one goes back on the shelf.
The optional rules may be able to handle this but the 15 hex supply makes the desert feel like the Somme...