You should PM Iguana as he was a truck driver for decades before retiring and writing truck-driver manuals(at least, last I checked).
My suggestions:- If you can't easily reach raw food outlets near your route, this is a problem. I presume that you are working for some fascist company that forces you, on threat of penalties, to stay on the route and reach your destination with no delays, unless you can provide a valid reason like a storm on the freeway etc. So, visiting farms is also out, though I would have thought, at least, that isolated farms on flat farm-land would have very large areas for parking lorries and the like.
Walmart is pretty crap. A few RVAFers have stated that they healed after eating raw, grainfed meats, such as is found in Walmart. Those are certainly better than their cooked versions. The trouble is that those same, raw, grainfed meats still do contain some toxins(as a result of the animals being fed on rubbish nutrition). Plus, grainfed meats taste foul compared to grassfed or wild meats - an important point to consider since most of us take time, as newbies, to get used to and enjoy eating raw meats in the first place. If Walmart also provides wildcaught fish, that might be an option, especially if you're near the coast, as it's always cheaper nearer the sea.
I don't think raw, nonorganic fruit/veg is the end of the world, though, given my own experience. By all means, buy that from Walmart.
You could settle for making pemmican, but a lot of RVAFers seem to do less well on pemmican because of all the cooked/rendered fat in it. A far better bet for you would be to make a huge amount of beef jerky and other dried raw meats(beef carpaccio, biltong?) and take it with you on your journey. Properly dried raw meats last forever. Lex Rooker has a link here on how to make your own cheap dehydrator:-
http://www.rawpaleodietforum.com/display-your-culinary-creations/lex's-%2410-beef-jerky-maker-and-recipes/Also, raw eggs can be stored for ages. Just make sure you get one of those large boxes which are designed so as to prevent the eggs from breaking. Can't remember what they are called, though.....