Just spent some free time, scrolling around one of those map apps.
I-5 has a whole bunch of stations through Oregon, both "official" (level 3, CHADeMo) and others (lots of level 2, and some level 1). They seem to be spaced nicely, even in the "green squares" (no offense). Of course, it helps that Oregon has good-sized towns all along I-5, so you don't get that green-square effect all that much. But still, there are points of some sort on the rural stretches, and it looks deliberate. Walgreens's company-wide rollout policy helps a good amount; after that are chargers at maybe every Nissan Dealer. Overall, towns seem to have enough stations that you'll find a level 1 or 2 somewhere, though the level 3s are few enough that you may be in contention with someone else. Haven't checked to see how many points per station. Strangely, Ashland has stations, but none appear related to the Brammo HQ. California and Washington don't look bad, either, but there are huge gaps in the Central Valley, surprise. Vancouver seems nicely represented.
On the East Coast, it looks like you could do DC-NY on a Zero ZF9, or an Empulse later. There are gaps around east Maryland/Delaware, mid-Jersey, and east Connecticut/Rhode Island, though. Don't know if you'd make it in an Enertia or Zero ZF6, especially in that NY-Boston stretch. Most are J1772- there are pretty much no CHADeMo, despite the Nissan dealers. Tesla might as well not have chargers, if this database is accurate.
Some of these station listings include rates, and a couple are ridiculous- one was maybe a dollar a minute. Hopefully that's the exception, not the rule.
Doesn't look like you could do cross-country, but if you tried, yeah, Tennessee would probably be involved.
Carlos