[TX] Split custody and want to change school districts. Advice on how to approach?

TLDR: I want to propose changing my kids' school district from where they have been since pre-k which is now struggling, to one that is prestigious and consistently ranked one of the state's best year over year. However, while I haven't brought up this school district before, my ex has previously told me she has no desire to ever move or change anything in the custody agreement. I currently drive 30 minutes to get the kids to school while she drives them 5 minutes. The new school would require her to drive 40 minutes. Any advice on how to propose this and any kind of incentives that would make sense?

Divorce was settled 5 years ago with 50-50 custody and ex is listed as primary. At the time, our youngest wasn't in school yet and our oldest was only in kindergarten. Current school is a 30 minute drive from my house and 5 minutes from ex's house. In this time, the school district has been struggling to retain teachers and has undergone 3 schedule changes (4 day school week, hybrid, etc) and the kids have aged out of daycare. I have noticed my oldest and most of his class do well on assignments but as a class average failing results in state testing. He says teachers never stay more than a year or two and teach in areas they aren't familiar with. I would like to enroll the kids in a different school district that is very prestigious (top 10 in state of TX) and has after school programs. However, my ex has previously indicated that she has no desire to change anything with the current custody agreement, and the new school would be a 40 minute drive for her. Any suggestions on how to approach this? I would be willing to compensate financially for gas, etc.

Additional info: After school care and transportation has been a point of contention after my oldest aged out of daycare. I have no family in the area, and ex's parents offered to pick them up and watch them after school. We argued all the time as they refused to follow any of the rules at my house around junk food, behavior, screen time, etc, to the point of telling the kids to not tell me about things they were doing there. I remarried last year and my mother-in-law has been making the drive to pick up and watch the kids on my weeks now. The new district would have options for after school programs, tutoring, activities, sports, etc.

The school district I am interested in is one of the best in the state, and known as an area that people move to because of the schools. The kids' current district is having financial problems and cannot retain teachers. The kids always have first or second year teachers, or teachers who have been moved around and don't know anything about the subjects they're teaching. IE, this year my son's former PE teacher is teaching him science. The kids in his class ace their assignments, but the class has a failing average on state testing, around 50%. He works hard to study, ask questions in class, do extra credit, does great in most other classes, but is failing state testing in this class just like the majority of his classmates.

Overall our arrangement is fairly amicable. Co-parenting attempts have led to multiple overreaches and boundaries crossed, but going more parallels parenting seems to be working. We don't always agree on each other's approaches to some things regarding the kids' health, safety, and wellbeing, but overall I don't think a court would look at both of us and say there is a legal need to change anything. I think my best bet is to work with a mediator to come up with some kind of offer. Any thoughts or advice?