Here's another notion now that I've had my coffee ...
What if multi-rank were done in conjunction with an RPS. So the ranking for P40's would include the P40B and P40E rotation of that plane up through the end of 1942 (when it ceases to be competetive). The Me109 Rank, though, would go from the beginning (109E4) to end (109K4) of the Tour. Same with the Spit.
Top Yak, Top La, Top Mustang, Top Hawker (Tiffy and Hurri combined), Top Late-War IJA (N1K and Ki84 combined), Top USN (F4F4 through to F6F), Top Corsair, etc etc ... a whole range of ranks suddenly become possible in a balanced way.
Some titles only span a part of the tour, some the whole duration, allowing a lot of depth in choosing what title(s) to go for. Obviously the top Spit title would be a crowded field, but Top La would only start in 1942-ish, leaving only a small window to compete in - which overlapped Top Yak title - which to choose? For the people who fly a ton, they could obviously go for more than 1.
You'd have to have ground rules, though. Like a player needs at least 5 kills in each variant of the plane that happen in a tour. No waiting for the La-7 to go for the La Title, you need to get 5 kills in the -5 too. And you'd need to differentiate ground targets from air targets.
How would this affect gameplay?
Don't know ... but it would allow the introduction of an RPS in a way that would add a lot of depth to the gameplay and would provide an incentive for players to stick with a plane type all through the tour, even during the period when it ain't Uber. And with more titles available and attainable, maybe people wouldn't be so quick to suicide themselves all over creation every night.
And for the veterans who don't care about ranks, well, we'd get an RPS and the opportunity to fly all the planes in a more balanced environment.