I'll try to help with the testing, but already FREDding for two projects and I really can't fit in the time for a 3rd. Or a 4th (since I'm also helping with BP multi testing when I can).
However, to save time on coop missions, you could look into taking some of the most difficult single player WoD missions and converting them to 4-8 player coops: For a quick and dirty conversion, just increase enemy AI classes by one level (where possible), increase wing threshold by one for some or all hostile wings with several waves, and up the wave count by a couple for some or all of the hostile wings. Then turn any originally AI-controlled friendly fighters into player fighters (up to a maximum of eight - twelve players requires more drastic measures), and you have a coop. It'll still need some fine tuning to balance properly, but it should be in the ballpark.
Alternatively, do some gauntlet missions. Those are simple enough in concept that you can get the framework for even a BIG one done in a day, and provide for good, mindless coop fun.