Why are you not making a major commitment in Western OZ? There are 3 potential size 9 airfields north of Perth and all are on rail lines so supply should not be a problem. They are Geraldton, Cue, and Meekatharra. They are all 8 hexes from Carnarvon. You have a number of aircraft that can reach using drop tanks and normal range, P-38, P47, F4U, F6F. With 3 level 9 airfields within range you can send 300-500 2 and 4 engine bombers over Carnarvon and obliterate it. March forth and take it. Supply will move slower but you should be able to move small supply TFs to Carnarvon. Use it to sweep Exmouth and send the bombers in later. March across the desert to take it and then press on to Port Hedland and Corunna Downs. Moving supply will be a bit dangerous but using Torpedo carrying aircraft like the Beaufort VIII( 8 hex range with torpedo ), the TBF-1 with drop tanks( 9 hexes with torpedo ) can make it expensive for Erik to try to interdict. Plus having large airfields with good fighters on CAP will help. And do not forget the USAAF attack bombers. You should be getting some B-25Gs now. Train aircrews up on low naval attack and send them in, 6 x 500 lb GP bombs can hurt a CV and they have a normal range of 11.
In SoPac you should be able to move further also. I would build Torres Island plus take and build Vanua Lava. When they are built up enough to support a number of fighter squadrons, move 2 hexes north to Vanikoro, build it and then take Utupua. These can all be level 6 or 7 airfields. The idea is to provide yourself with LRCAP that only has to cover 2 or 3 hexes. LRCAP is more effective if it is operating at close range. Only then move and take Ndeni. I would take Reef Islands to provide a forward base to put search aircraft and a set of fighter TBF units to help protect the Santa Cruz Islands.
The next step in the SoPac is a hard one. You would need to take either Rennell Island or Kirakira. Both are a long step, but once you take one or both, you will be able to move slowly up the chain of the Solomon Islands.
I hope this helps you Jocke.