Sure, it's doable, because he's not riding the whole way. His Dec. 29 post on his website has the following, which was prior to his accident later that day:

"Two hours later I convinced two truckers named Ed and Jan to give me a ride down the road about 20 miles to the next big truck stop.
Simply put (I’ll spare the hitching stories for another time), after two more rides across spans that are impossible to cross on the I-10 I finally got to Baton Rouge and reunited with Josh, who had lucked out in his hitching expedition and was waiting for me at the Chimes Bar next to Louisiana State University. After finishing the local brews and gumbo, we headed out to our host’s family five miles away."

A reasonable person has to wonder just how much he's been riding, and how much he's been thumbing. He seemed to get across Mississippi awfully quickly. Does anyone really know if he biked the mountains of New Mexico, or the long stretch of west Texas? And then, of course, there was the car trip from the California desert to Phoenix.

I've heard that tattoo removal can be quite painful.