Do You Know Height of Your Trailer?

We sometimes camp at Hamlin Beach near Rochester, NY. The parkway that goes by the park has some quaint old stone arched underpasses. My little Fun Finder easily passed underneath, but I thought many 5'ers would never make it. I asked another camper with a nice 5'er about it and he told me he had to come by another route. He also told me he had a GPS that would route him around any underpasses that would not accommodate his rig. Seems like a good idea to avoid the situation entirely. The only thing worse than backing up a big rig would be making a U-turn in front of a low overpass.