Piece of tape "no zigzag" to remind you.
My hubby had an accident with our horse trailer - he was uninjured, the horse trailer was destroyed, 2 horses were badly injured, but totally recovered after several months of me playing horse nurse (am really an OB nurse), for Vet prices with which we could have purchased new horses. LOL
My point - he now has a multicolored piece of posterboard he sets up on the dashboard of the pickup that says "HORSETRAILER" as a reminder whenever he trailers the horses. :+) Works for him.