You shouldnt have to sacrifice, it shouldnt be part of the score. If I'm number 1 in vehicles or bombers I don't want to have to avoid flying a storch or supplying a strat because it will knock me down to #2. Per sortie stats are so important for the top ranks, as it stands now the top players hurt themselves by doing grunt work.
Then you could also say: "I want to fly a Boston, but that will hurt my bomber rank #1" (or a P-40C, for fighter rank)
Going for #1 is a very special task all by itself. It's you deliberately playing the rank game and that could possibly prevent many things that one could consider "fun" or important. For example, babysitting a maproom at a WF town will 'hurt' your vehicle score the same way. If empty sorties bother you that much, you could not do that either.