Find Portree's monograph for more context. I have started writing about these studies. I have the big study that was done first. The spacecraft for that were huge, and would have required substantial new ground infrastructure (more Saturn launch pads, enhancements to the VAB, etc.). Von Braun's people then scaled it down. I want to understand how the von Braun version got scaled down. I got some information indicating that part of it was choosing a different orbit that reduced the fuel load. They also made some other choices that led to a smaller vehicle. But it still would have been massive.
What I have not found is any definitive report that details von Braun's version. There are slides and sections of other reports, but no 500-page engineering analysis, like exists for the earlier version. They obviously did the trades, but I cannot figure out if they never produced a final report or if they simply went to briefing slides.