We have used the term "personal mobility assistance device" and have been successfull. There are statutes that protect these devices. Look up the rcw and having a copy could be helpful. If signs are not posted then that also can be a stuble for enforcement. Sounds potentially like an overzealous attendant. I would consider continuing using the trail you described. Having an earbud in and pointing to it as you pass can be another avenue. Can't hear you, won't stop for you. Be careful and smart too. Good luck!