Coming back from a 28 days around the USA trip, I wanted to add two little things to this topic.
First, about Truck Stops, here's a site I, sadly, found too late which has all the link you gave on the same page: http://www.allstays.com/c/truck-stops-locations-map.htm
And for wi-fi, what I did was to use the Starbucks. You get free wi-fi and the only conditions is you need to have used your Starbucks card in the last 30 days. So I bought this card (the card itself costs nothing, you have to add value on it, so I put the minimum: 5$) and bought a coffee the first day. Then everytime I was close to one (and they are everywhere, especially if you go to relatively medium/big cities) I went there and just used my free 2 hours of wi-fi per day. Never got bothered by the employees for not buying anything but if I had been, I would have bought a coffee (which it's still cheaper than paying it at most hotels).
To find if there's a wi-fi Starbucks near your location, go to their site: http://www.starbucks.com/retail/find/default.aspx and check the wireless hotspot box.
Hope that can help.