Originally Posted by Jim34RL
I use a Rand McNally GPS unit for RV's. In the RV set-up section the user states the parameters for the camper such as height, length, width and so forth. The route for towing is than computed by the GPS using these parameters. So far it has been accurate, but I still use paper maps and common sense.
I also use the Rand McNally GPS (7720 I think). One caution - it will only route you around low clearances IF you are following route to a specific destination (e.g. the campground). If you are just using the map feature and driving around, it will not warn you of low clearance.
Another good resource is a Truckers Road Atlas. Has low clearances listed in a table by state, then by highway and location.
Jim - I'm from Oswego, NY.