Looks like the entire map is in play. Squads likely should plan to RTB TO THEIR ORIGINAL DEPARTURE FIELD, as "extra" bases not used by anyone or designated for specific aircraft types are few and far between. "Transit time" cycling fighters for ammo may be a significant factor in this Series. Axis fighters have significantly less time involved in returning to the "front" than will the Allied fighters. In available fighters, with the 100% fuel requirement, ammo will likely be a bigger problem than endurance.
Differing from the "Planning Map" Grass Field F-7 in the 4,3 box seems to be available for Hurri IIB aircraft. Fields in the Tobruk area also differ. Alternately stated, the "front" must sag to the West in that area to accommodate Field F-7 being under Allied control. Red dashed line indicates the difference between the Online and the Planning maps.