You’re on the right track. Bringing Mass-appropriate things to look at/use, going to a daily Mass for practice in smaller bits (and for worship), sitting up front and taking notice of the bells and whistles, etc… Also, personally, I would set some goals - see if you can hold her off a little longer every few weeks. So if she is used to being good right up to the beginning of the homily for a few weeks, start aiming for making it 1/2 way through. One way to do this is to hold off on giving out the toys at the beginning of Mass. Don’t give them out right away. Wait a little bit, allowing the child to practice good old fashioned patience FIRST, and see how long you can stretch that time out. Other than that, yes, you might be stuck separated from your spouse, with one in the back of the church (until your little one is a little older - then maybe you’ll meet up back there!). As the others said, don’t let a toddler down in the back if you can possibly help it (sometimes you’re outnumbered, or exhausted, but as a rule…). Learn the “death grip” (you know, the hold that never loosens, even when they squirm, and that gets more uncomfortable for both of you the more the squirm), and use it whenever the child is misbehaving.
My kids are pretty good in Mass. I think that my dh has gotten soft on keeping them in line over the years though, and my 2 younger ones are taking a little longer to learn than the 2 older ones did (my dh would disagree with me, but he’s not here to argue, is he?, lol). Our 3yo usually sits with dh, so that I can sit with the 6yo and keep her focused, keep the 3yo away from her, and help her to learn what she should be doing. Well last Sunday, I was the one with the 3yo, and we were at Mass in the evening (you know, the witching hour). The 3yo was not following my directions, and she was being way to disruptive to me and requiring too much correction. So I picked her up in “the death grip,” which became more uncomfortable (for both of us) the more she squirmed to get out of it. Since she hasn’t had a lot of death grips (like I said, dh has gone easier lately), she really struggled (boy was I grumpy). At some point, she looked at me, and said in her most plaintive voice, “Why are you doing this to me?” And I answered, “because you are misbehaving.” She did calm down a bit, and I suspect that at her age, she has already taken something from that event. My guess is that if I were able to do that do her consistently, she would improve quite a bit more quickly than she is. I only wish I had used the death grip more on my 6yo - unfortunately, I was preggers and nursing the younger one when she was in need of the death grip, so she didn’t get it - and I do notice the difference.