Here's where you lost me. You're basically saying that all reports in Minnesota and Iowa are hoaxes because they fall into group B. I disagree. (I don't care as much but the logic also applies to Michigan, Illinois, Ohio, and Wisconsin)
While the methods you used might be sound, the data really needs to be adjusted. Here a few reasons I think the conclusions are off.
1. There are many encounters in Iowa that remain out of the public BFRO data base because they'd give up expedition locations. You'll see some of them when Finding Bigfoot Iowa gets aired. I can think of 7 or 8 encounters that happened while I was present, that would all be good enough to make it into the database (knocks, whoops with audio, and class B sightings which as shown in your report cannot really be attributed to black bear). In Minnesota, the BFRO presence has dropped off to form other groups that are taking reports and holding expeditions (one of which I am a part of). Reports that they receive don't make it into the BFRO database. When Finding Bigfoot rolled into Minnesota they looked to at least one of these other groups for potential locations and witnesses.
2. If your conclusions are somehow based on population, it needs some tweaking. The residents of Des Moines and Minneapolis/St Paul make up a large population percentage of both states, but the sightings are (generally) far away from those big cities. If you want to conclude that Des Moines and Minneapolis suburban sightings are hoaxes I can live with that. Take away those big cities and your population density for the rest of the state falls off greatly I'd suspect, and mostly likely changes the conclusions. (same argument for Illinois, Ohio, Michigan, and Wisconsin)
3. I think you somehow need to account for percentage of forest each state has. Iowa has more forest than you'd suspect, but I'd guess it's a pretty low percentage of total area compared to come other states. I'd like to know how the sightings per square mile of forest works out for all the states. (I may look into that actually) That might work in Iowa's favor but hurt Minnesota.
4. South Dakota as an A' while Iowa, Minnesota, Ohio, Illinois, and Wisconsin are all 'probable hoaxes' is a huge red flag. Sioux Falls must not be large enough.
There's probably more and I don't have the know-how to figure out exactly how this all fits in. I just know the initial conclusions don't fit my view of reality.
Edit: I left off rain totals, which I'm pretty certain matter greatly...