Anyone use a laser measure to measure height or clearance?

I've used 1/2" pvc pipe the length of which is equal to your travelling RV height. I had two pieces joined with a connector. This means you have to get out and manually check for clearance.
Place one end on the ground under the clearance in question; if the other end clears it then you are good to go. Personally I've only used this in campgrounds for tree limb clearance. This was in the Trailer Life mag a few years ago.