I spent some time working for a charter carrier after my furlough. They wanted to know my mil days before the monthly schedule - then they just built it to avoid my mil.

I think it would be similar with any smaller outfit. You're just going to be more visible and typically those companies aren't manned as heavily. They're going to be more sensitive to schedule disruptions and you probably won't have as much flexibility in schedule changes as you might with a larger airline. They still have to give you the mil days, no changing that. However, depending on the company and how they schedule, you may find it hard to avoid working mil days on your days off. Especially if they ask for your mil days before they publish your schedule.