How can I force an outdoor plant into flowering with almost 14 to 16 hours of sunlight per day
Using an artificial shadow with an opaque object, in the first or last hours of sunlight. Example: plastic opaque on top of some bamboo canes , making easy to cover the plants and also being ventilated,if the nights are cold, lower than 18ºC i recomend keep the plastic on the plants nights. I remember having seen a photo in this forum, just with the idea, I keep looking.
For 100 plants?
If you are in 14-16 hours of sunlight and you want to make it bloom ,yes.
if you only can choose some part of the plants, choose the more sativas first, indicas are fast bud and normally starts before in outdoors.