Before I get too deep into this I'll let you know the direction I am going in.
Setup A: July 15, 1943 The allies already have a beach head. The 31st FG has moved to Ponte Olivo on Sicily in their Spitfires. P-40's with the British Desert Air Force have also moved to Sicily.
The P-38's of the 82nd, 1st and 14th FG are supporting the bombers out of North Africa. The US bombers used were the B-17, B-26, B-25 and A-20, none stationed particularly close to Sicily.
Hurricanes were also involved as well as a bunch of aircraft not in the plane set (A-36, Blenheim, Baltimore, Beaufighter, Wellington)
So with this setup the Allies start with a foothold in Sicily and some aircraft on the island but only second line fighters (Spit V, P-40, Hurricane). The rest of the air assets are off island.
The Axis would have the C202, C205, 109G6 and 190A5 and Ju 87 on Sicily itself and all bombers (Ju88) back in Italy. The 109G6 was definitely on Sicily at the start of the invasion.
Ground Vehicles I would leave up to someone more versed than myself with the gameplay issues associated with them. No C47-s so capture would have to be done by ground with rebuild times that would make that possible.
I don't see any P-51 units involved in Husky but there were A-36 units but the P-51B isn't a suitable sub for the A-36
I think the Allies would have a pretty tough fight to maintain the beach head. Ordnance available on the island for ground attack should reflect the limited supply situation while off of Sicily the allies would have a very good supply situation. The Axis would have a good supply situation on Sicily and ordnance should reflect that.
If this sound reasonable I'll work up a base listing with aircraft.