I got rid of my windshield mount a long time ago and replaced it with a laptop based navigation system. The main reason was offline use, the large screen, inexpensive updates and ease of importing / exporting / overlaying data, plus synchronizing with a handheld GPS. I use both the
Delorme Topo and Street Atlas products.
Microsoft Streets and Trips was a good product, but they are leaving the business in mid 2015.
You can download for free, drawing overlay files from various websites by searching for "POI" (points of interest) where someone else has already done the work for you.
Aside from POI Factory, I like the
Discovery Owners Association site. They have a section with lots of RV specific overlay files, specific for various devices / programs, along with instructions how to use them. I used so many of their files that I gave them a file I had created for all the ski areas in the western US and Canada.
Alternately you can call/email various agencies and they often have lat/lon coordinate files that you can use to create your own overlay files. Note - some of the USFS / BLM lat/lon coordinates on their sites are not correct, so if you are planning to go way out there, a quick look via google earth before leaving is prudent. As is stopping by the district ranger station and asking about the latest road conditions and their thoughts on your route.