The only problem I have with the "Add in high altitude plateaus" solution is that it leaves other low altitude aircraft still screwed.
If you happen to prefer the P-40E, Mosquito Mk VI, La-5FN, P-39 (when it is added) ect, ect you still have to face the full fury of the La-7s.
The high altitude aircraft like the P-51D, Spitfire Mk IX, P-38L and P-47D will all get a good boost though.