My son had the potential to be in the middle of a situation between school and travel ball. Don't forget courses taken at school are for credit and required for graduation.
My son went to both coaches. He talked to them regarding fall ball. He needs to showcase this fall as a position player. He needs to prove to the high school coach he's ready to be a starting pitcher (junior year). He worked out an accomodating schedule with both coaches.
He had the same situation with physical workouts. When he explained to the travel coach the workout his high school program would be putting him through (FASST - fitness, agility, strength, speed training) three times a week, he was told not to bother coming to the travel team workouts.
Good coaches don't want their players to get injured.