I believe the reason that the Gainesville and Giddings State Schools (I believe they have a new name) are members of TAPPS, as is the Texas School for the Deaf in Austin is that at the time TAPPS was formed, the UIL had (and may still have) a prohibition against prison schools and boarding state schools in their bylaws.
TAPPS took these three schools into their organization as as I can remember, they have been an asset to the organization ever since. TAPPS bylaws now prohibit tax supported schools (as these three) as new members, but these three have been "grandfathered" in as they were members at the time that restriction was imposed. I remember a couple years ago, another youth correctional facility in NE Texas was considering adding six man football, but the facility closed prior to that decision. They could not join either TAPPS or UIL.
The folks that coach and teach at these schools deserve our thanks and support, as they have a very demanding job and the opportunity to truly turn a young man's life around from crime and violence to being a beneficial member of society. I'm sure they can tell you better than I that it doesn't happen as much as they like, but they do make the effort.
About 8 or 10 years ago, ESPN did a great series on the Giddings team, then playing 11-man. They had a very good season and moved deep into the TAPPS playoffs. If I remember correctly, they had a very talented young man that played quarterback. A few days before the next playoff game (perhaps the semi-finals), his term at the facility ended and he was released. And therefore, under the prison rules, he was not allowed to associate with his teammates or participate in the next game.
A few years later, one of the DFW TAPPS schools did a great service to the young men from Gainesville. Those teams, shall we say, don't draw well at the gate -- occasionally a parent or two, but the bulk of the visiting fans are actually prison guards. The school decided to "lend" half of their fans and cheerleaders to the Gainesville school and cheer for the visiting team. Following the game, the visiting players were provided a meal and a Bible, and a number of TAPPS schools have followed suit in the years that followed.
Chances are, if you're playing one of those schools, you probably are going to have one of the cleanest games because what a referee or coach can do pales to the response from the administration at the school/prison. I doubt you'll see a high school version of "The Longest Yard."