Sadly you will find many parks with size/ breed restrictions. Of course there might be restrictions imposed by insurance providers, or the local AHJ. Perhaps its the camp preference.
Whatever the rule, it is within the rights of that entity to restrict any animal.
Sorry, but your Fido might be amongst a well documented group of breeds that are well known to be potentialy aggressive.
The broad brush of breed propencities cannot be erased with your assurance about your pet.
Good Luck in your travels and in educating those you meet about your amimals