I always wished to see in WOFF historically correct planes and squadrons on airfields at given campaign date. Now, with version 1.1.9 of Mission Editor, my dream finally materialized .
You can download complete WOFF UE_Mission_Editor v1.1.9 here:
WOFF UE_Mission_Editor 1.1.9
To enable above mentioned feature, just click on OK button at "Populate airfields..." popup window during mission save dialog.