Not hard to regulate it at that level.

1. require a special license to operate a gym of any type
2. require background checks
3. Have a door colour system similar to restaurants based on that system (red = you pay your dime, you take your chances/ green = this is a lawful institution)

That should start it an prevent any tom **** and harry from providing services without the checkup.

I can't get a desk job without a police check why should someone jut start a business with access to kids an not have that same requirement?

Post your police background check on the wall.

It's only 40 bucks or so to get it.