Dear sorry about that,
This is way a Yellow Pages question, if you were wondering, and let me explain why. First, I've contacted my friend who was pretty serious in gymnastics all growing up, and a lot of what she has to say may not be news to you, but these were her comments:
It depends on what level they compete - Level 4 generally competes on Sundays, 5-6 are more Fridays and Saturdays. The way we did it in my family, I never competed Sundays unless it was a qualifying meet - like state to get me to regionals, regionals to get me to nationals, or nationals. That was only when I was an upper level gymnast and looking for scholarships, and it helped me to walk onto BYU's team. It's a personal choice, there was one gymnast at BYU from California and she never competed on Sundays. She also never went to any big meets, but because of her skills she was able to walk on. I never had to deal with it because I just skipped it and the gym was fine with it. If the gymnast is good enough, they're going to work with him/her. If they won't, it's time to look for a new gym.
Which it appears is what you're doing, but she offered to call you and tell you her experience with things if you want (shoot me an e-mail at stillsbyolympus at gmail dot com). In any case, it sounds like this could be not a black and white issue for each gym you'd call. Me, calling to say, "Do you require Sunday competition? ...OK, thanks, bye." will probably always get a "Yes." You, calling to say, "Hi, I'm a level x and I'm moving into your area, I'm looking for a gym and here's my situation, can I come show you what I can do and we can talk about it?" might get a totally different answer.
I didn't want to make you wait longer for this question, so I'll let it post, but if I get the contact information for the gymnast from California or more information in general I'll post it as a comment.
Here are my resources, feel free:Google's hits.
(To get you started, the first hit requires Sunday competition.)Super Pages' hits.IAF.net's hits.
Those are some good beginnings for Elk Grove. I think you could use the same tactics for Sacto.