John, for heaven's sake there are no mountains between Chicago and New Orleans. Some rolling country in Tennessee, sure.

The paranoia on this thread is unbelievable. A polite fellow will find, as we all do, that 99.9% of people he encounters on the roads are not out to 'get him'. If there are stretches full of lowlifes, well, I imagine if he keeps talking to people along the way, he can easily get rerouted or score a short lift through such areas.   And once you hit the south, half the law enforcement officials are black, so let's can the "heat of the night" tales, for God's sake. And most Americans are utterly fascinated by English accents. He'll be the 'talk of the town' in some small towns and left alone in suburban sprawl.

Use public libraries, courthouses, and gas stations for bathroom facilities, and visit fire stations and antique stores to find people willing to talk. Keep a credit and debit card tucked in a sock so you don't get stranded without cash.

Plan to camp out as much as possible in state parks, and in National Forest campgrounds, and there are also some Corps of Engineer parks and county parks few people know about, etc. Find the whole network and map it out. Ask at each one where your next stop should be. Some town parks also allow low-profile overnight camping upon request, and if farmers or suburbanites get to like you, they'll also allow camping on their lawn or fields.   

If the fella is shy, he'll have a long tough trip. If he is willing to chat up everyone he meets, angels will guide him on his way.