Perhaps I've watched too many "apocalypse" movies .... but: With the U.S. having so many 4WD vehicles and guns within it's population ... roving gangs of brutal and heavily armed people will be able to get everywhere and hence will go everywhere and find anyone with provisions no matter where they are in an RV or otherwise. I wouldn't count on hunkering down in any RV or expedition type vehicle being much protection very long when and if the "big one" comes ... it's too late for that to work in the U.S..
That being said, I agree that the map might be a great boondocking map by looking for spots outside the circles .... assuming you will not need to be closer to a city in case of RV breakdown problems and assuming you have a body that will not need to be closer to a city in case of body breakdown problems.
That reminds me ... just a few days ago I received in the mail a brochure on Good Sam's medical assistance service. It is an interesting and tempting service, whether you're old and like to boondock camp or a young immortal who likes to boondock camp. :h