At Ray Chapman's school those that used DA/SA did learn to cock the weapon with their off thumb quickly (and Ray used a 92 Beretta with a Bar-Sto barrel to demonstrate) and we did an awful lot of shooting for a week (as well as two nights.)
Yes you can cock it under stress, but most of the time it's unnecessary as the ranges are close.
May I also suggest going to an indoor range during their off hours and have them turn their lights on low. I've done that many times. Good training.
"The government has confiscated all of our rights and is selling them back to us in the form of permits."