Having worked non union for a while, as well as ameature - I can tell you now - non union can be the pits for SM's -
ie that lighting plot starting at 4pm, after focus, which is scheduled to finish at 7pm, often ends up going till 4am in the morning - now as SM, I ensure I am there from start to finish of that day - and the fact that I have a sound plot the next morning at 7am, means that I drive home from the theatre, and basically get to bed by 5. Then I have to wake up a 6 to get to the theatre by seven, and what is in my pay cheque - standard 9-5 pay. Sure it evens out a little bit - I may get 9-5 pay for some days where I ONLY do 4 hours in the afternoon - it depends how dedicated you are - I love stage managing, and tech week in general, so I am happy to sleep on the crash mats in the theatre to get the extra 2 hours sleep. I would break the union rules with the hours I do - currently I do quite a bit of ameature work, which is usually a bit better - they are usually booted out by venue techs at midnight.