Hi Edward,
Here is what I do in CUP #WAW with MissionPro on.
I do not use stock IL-2 at all and only fly my own map, in CUP #WAW.
So I cannot comment on stock maps or the influence of MissionPro... sorry!
I do spend a terrible amount of time testing my newly created airfields, mostly to check how planes will taxi to park on landing but also, occasionally, some taxi to take off testing when spawn points, runways and taxiways are complex.
I generally can get about 32 planes (fighters, transport, attack, bombers) to take off from taxi positions on a circular shaped airfield like
Lodeynoye Pole, taking to the skies from 2 different runways. This includes the player aircraft and takes a looooooooong time to get right! All taxiing is done from stationary aircraft placed on spawning points.
My conclusion is that if you set it right (by spending a ridiculous amount of time) in your mission, with a sound airfield design (in FMB+), pretty much anything can taxi and then take off. A particular trick is to have a straight section of taxiing with 3-4 waypoints before the actual take-off waypoint. The very fact that you have to spend so much time to get it to work also indicates that it will be near impossible to automate (using DCG, DGEN or QMB).
Over time, for map creation, this has led me to do less taxi-to-take-off testing and focus mainly on the landings/parking.
It must have a therapeutic virtue of some sort for me to watch planes land on IL-2 for hours...!
By sound airfield design I mean applying the principles set out in
https://www.sas1946.com/main/index.php/topic,14115.0.html by spdr109. If you go through the thread you will see that stock airfields can have their problems.