You don't have a lot of options at this point. Lets hope the facility will end up kicking them out as enforcement because it sounds to me they are the type who will not follow the rules no matter what.
Go out and get yourself some mace/pepper spray and nail that dog if it so much as glances at you or your dog. I would then go door to door and recommend everyone else does the same. Maybe some public shaming will work but if not at least everyone has been warned and have a chance to arm themselves if they wish.
FYI, keep documenting everything even if it's just in a personal journal with time/dates in it. Wouldn't hurt to get picture evidence of the dog running loose all the time too. This way when something happens you'll have some sort of proof to fall back on. This is actually advice lawyers give to those being abused, stalked, etc so it should work in the case of dogs. Why do I say this? I bet they are also the type to sue if something happens to their precious dog.