I got one of the Rand RV ones about 3 years ago from CW. Used it while traveling in our fiver and now have changed the inputs for our Challenger.
In probably a little over 20,000 miles of using it in 26 states it only missed one low clearance. Thank goodness that was in a city and I saw the sign in time to avoid damage.
It has worked very well, is large and visible, and I have gotten probably 3 free updates so far.
Full Time in 2017 Newmar Ventana 4369
pulling a 24' enclosed (Mini Cooper/Harley/Kayak)
(traded 2014 Thor Challenger)
US Army 70-73 Retired LEO