The problem is that Mission Editor does not know ranks of historical aces (it is not written/stored anywhere), so, it can not assign proper aircraft without this info. The WOFF formula is simple - if you find HA in sqaud roster, assign him the best aircraft available.
Also, ME does not store data between missions and does not know what aircraft you have assigned to your squad pilots before. The only way I can see is to assign airplanes to your pilot before each mission from drop-down menu list.