There used to be a commercial add-on by (I think) Alpha Sims called (I think), "Combat Aces." By all accounts, it wasn't very good.
Your best bet may be to create your own missions and campaign in CFS2.
I personally just fly my WWI planes in CFS2 in quick combat mode. That's about all I have time for these days. I work full-time, have a wife and a baby, and I'm in grad school.
On the plus side, my 3.5 month-old son loves to sit on my lap while I blow Fokkers out of the sky with my Spad!
Regards,