I think it is important to let individuals know that is what you could be doing. If they're not there, there should be supplementary paper that states it was for training.

Also, most places from what I can tell do not recruit daytime businesses in their area. You can have a much larger daytime population, but everyone you have trained is not where you need them. Approach businesses about being a good "corporate citizen" and allowing workers to be available for local emergencies. The employee can do the training on their own time, but work can give them time off without penalty. The best way would be offer training in the immediate area of their business so they can attend easily.