I'm also a non-camper. What I did was to have a plan A, but to be flexible. This involved setting out what I thought I would likely do every day of the trip, with stop locations. I would book motels 5 days in advance on a rolling basis in case it started to become clear that I couldn't make the schedule (using something like bookingdotcom*). This allowed me to know if I needed to split a stage into 2 for 2 easy days, and so book an extra motel, or to re-route by reducing distance one day, but increasing the next.
Having the overall plan also helped me to understand which areas are pinch points. Re-routing and finding a different motel in Kentucky is no problem at all. Doing it in Wyoming or South Dakota is much more difficult. There were some areas where towns are 50 miles apart. You either stop, or you carry on to the next. Some of these places had fairly low availability, but booking a few days in advance was fine, except Rapid City in August (Sturgis Motorcycle Rally). You can also consider AirBnB for rooms in houses, or WarmShowers. Rather than ride from motel to motel, just sit in McD's for 30 mins on the Wifi to look online.
Also consider staying at National Park lodges. They can be a bit expensive if you are solo, but they are in some spectacular locations.
Another option is that you could do this as a roadtrip with family who aren't inclined to cycle across the continent, so bring a convenient car.
Or you could hire a car yourself if you get into problems. It is possible to hire a car in location 1 and drop off at location 2. You could use this if you've fallen massively behind schedule, or if you are struggling for whatever reason. Again, you could sit in a McD (free wifi and free refills) to find options online.
*If using booking websites, beware of towns with the same name as another town 30 miles away. This happens in the US more frequently than you might think.
