Re the Ketterkrad, Yes, I want one, and no, I don't think it practical. It is kind of a unique tool, customized for the job.
I saw the description of the "new" USA, toward the end of the story... Too bad there wasn't a series of nuke triggered earthquakes to sink California... My experience of the eastern US is limited and, overall, I see it as a hugely overpopulated trap for those living here now. Since the story centers around Missouri, (lower population, moderate climate, tornado country), it made sense to locate a BOL there.
As for putting the new capital in the center of the country, that makes more sense than our current setup.
The logic of consolidating various of our current states into new configuration seems like a thing with should occur (given a SHTF event on this scale). Since this is a very politically driven topic, my bet is there would be more opposition and fighting between the various groups before the "new" arrangement was agreed upon. The description of that process, in the story, was more compressed than reality. For those of a political mindset, that would have been an entire book in itself, or even a series. Thank for your NOT laying out the whole process in the story.
Overall, the splitting and re-configuring of states will be driven by population density. Where you have many people, there will be multiple groupings according to social and political opinions. Another reason to avoid the eastern US.
For the western US, the number of people is already smaller and I would expect to see larger "states" being created, sort of like the land rush days of the 1800's. Those with the power and tools will assume control of large estates.
Within the story line, the weather drove much of the population movement. People when where there were food and supplies. Given that the 'nuclear winter' was of limited duration, the western US is still a dry area while the east and south-east have better agricultural climate. This dictates where people CAN live well, as opposed to where they might have lived before SHTF.
And I also want to hear what readers think of the use of gold and silver as currency.