I would tend to just wing it much of the way if not following a standard route. Even when following an AC route I tend to wing it for some sections.

In case you are not completely decided on doing your own route, I will say that a big part of what made our Trans America special was that we were on a route frequented by other like minded folks. I have done tours on AC routes and tours not mapped by AC and based on that experience I have to say that the Trans America route was something special. We did depart from it for a few hours or a few days here or there, so we got the feel of that too, but we met some good friends along the way and enjoyed comparing notes with other riders.

On the Southern Tier I was off rote a lot more and I don't feel that route has the same special quality of camaraderie as the TA does. If doing the ST again I might wing all or nearly all of it, but for the middle latitudes of the country I highly recommend riding at least a significant portion of the TA.