The governing body for public high school sports and activities in Texas, the UIL, has declared that soft shell caps, such as those manufactured by Guardian, will NOT be allowed for student-athletes at their member institutions. This is regardless of where they are playing, i.e., if they play against a team that belongs to an organization that allows such caps, the UIL team is still prohibited from wearing them. The non-UIL opponent is not governed by UIL rules, and may wear them, even at a UIL site.
The primary governing body for private schools in Texas is TAPPS, and they will allow the use of such caps, with approval from TAPPS, per player. The team must present the Referee with an approval form, signed by a TAPPS authority for each player that will use such a cap, at each game.
So, we will have, at the very least, some UIL schools playing TAPPS schools, and the TAPPS schools may use them, with TAPPS approval forms. UIL schools may not - period.