If you want to reduce the mileage, go from San Diego to Charleston, SC. It's "only" 2200 miles -- the shortest distance across the U.S. There's a good book, called "Over The Hills" by newspaperman David Lamb. He rode across the U.S. training as he went -- no preparation. He was also 55 years old, and smoked and drank alkyhol all the way. He said in the book that the eastern Appalachians are worse than the Rockies. The Rockies are gradual, but the Appalachians are "straight up!" It took him two months.