I will be going across America on the southern route, April 23 to May 20.
This is a fully supported tour by America By Bicycle.
I added this to Mentor 58 information above so you are aware that there are faster tours available. I also know people who have done it on a Tandem in 11 days.
(I cannot do that)
My tour requires 100 to 150 miles/day. To be comfortable one is supposed to be able to do 100 miles in 6 to 6.5 hours. (I can do that)
Oh, by the way, the base cost is $5000/person not including lunches and getting to the location.
Perhaps this helps?