Your biggest problem is going to be getting a support vehicle and someone who can take three months off of work to do it with you, with said person being a trained medic or at least someone who has experience with extreme foot injuries and blistering, there are portions of that treck in which you would be walking from the moment you get up till the moment you sleep, several days just to cross a section of land where every single mile will feel like then mile before it.
Personally I think it's too much to try off the bat, you're not Forrest Gump, maybe repeat the previous walk a few times in preparation, such as repeat it but once you arrive at the destination turn 180 and walk back, because when you make it all the way back you'll have done roughly 1/8th of the distance needed for crossing America.
So support vehicle and medic for 3+ months food and water for at minimum, 2 people for 3 months, medical supplies, fuel, good tracking and mapping, all as just a bare minimum.
