I think you need to look outside the box a bit, ALL the issue's addressed by you were dealt with, all I'm saying once the Spitfire and Hurricane changed from the defensive in 1940 to offensive 1941 they didn't have the range to do it, the Americans on the other hand didn't stuff about, they got straight into looking at ways to extend the range of their fighters which eventually led, even with all it's issue's, to the VLR Mustang.I dont know why the Spitfire gets it in the neck over range all the time, Allisson engined planes dont for their lack of altitude performance without a turbo. Until 1943 only the P-38 had range and high altitude performance, the P-47 didnt appear in service until April 1943.