Many on this forum have provided insights on taking trips in the Model S. Out here in the Midwest, we have no Superchargers, and a sprinkling of Level 2 charging stations in our major cities.
It appears that the RV site route is the best solution for charging on a trip. I have made calls to various campgrounds, and get very different responses. They range from "no problem" and it will be $5 per hour for a 50 amp circuit to "nobody has every asked us about this, but we would have to charge you $40 for an overnight campsite.
I sent a note to KOA yesterday suggesting they actively market their RV to EV owners. If you own a park, why wouldn't you rent out an empty site for a few hours for $5 an hour or so? It would also be great PR and put a high tech, forward thinking spin on their brand.
If nothing else, KOA could send out an information bulletin to their site owners. They could also get listed with Plugshare and the DOE site.
It would be great if anyone on our forum has a contact at KOA corporate that could get this message up the chain.