High school ball takes priority during its season. The only possible overlap would be at the end of the high school season and the beginning of travel. High school should take priority. The travel coach should respect the end of the high school season. But communicate with the travel coach.
My son played high school soccer and travel fall ball. Soccer always took priority. It was the sport in season. But once again, communicate with the travel coach.
The high school had a fall ball team. Established players weren’t expected to participate unless they wanted. The team was more about prospects moving up. Established players played travel fall ball. I believe my son clinched his starting position soph year playing fall ball for the high school team. It made spring tryouts a formality.
The baseball program also had winter workouts after school and twice a week at 6am. Players weren’t required to attend. But they were warned they better show up for the first day of tryouts/practice in opening day playing shape.