Either make it USAAF vs Luftwaffe (a perfectly fine setup with an obvious focus) or put the Brits in it. Putting the Brits in it, but only back in the UK and calling it Allied is absurd.
Spitfire XIVs, LF.Mk IX/Mk XVIs, Typhoons, Tempests and Mosquitoes were all ranging over that region at the time specified. Including all, or any, of those doesn't work as it makes the Luftwaffe have to deal with fast P-51s and turny Spitfires all mixed in together.
Such scenarios are much better, in my opinion, as USAAF vs the Luftwaffe or as RAF vs the Luftwaffe and no token Spitfire or P-47 (I know the Brits used them) tossed in to make it "Allied".
That said, I know the AvA has an extremely strong anti-Spitfire bias (loving to use 1942 Spitfire F.Mk IXs all the way to 1945 and cluelessly justifying it based on the it being a "Mk IX" as all Mk IXs are the same, just like all Bf109Gs are the same), so it is hardly surprising to see the attitude you exhibit.