Lots of debate about rust inhibitors. It doesn't hurt. There are many frames that have endured decades of abuse without the inhibitors. Your frame won't rust out on this trip. But, you do live in Chicago where they salt the roads, so it may not be a bad idea if you ride in the winter.
I was think more in general for greater longevity rather than just for this tour. I don't really bike in the winter, but I could see myself doing so in the future if I end up in a more bike friendly area.
I have started carrying
Park Boots. They are easy to carry. About 2x as big as needed (so far). If used as a long-term repair, they will eventually chew through a tube (1000 to 2000 miles). There are a lot of DIY boots that may be just as effective, including MONEY.
I've heard of money for a boot. Thanks for the reminder.
Even if you finish the trip on the original tires, you may be ready to replace, so a set of spares at home isn't a bad idea.
The grand plan is to do the US this year and Europe the following. Maybe I could save my current, more road oriented Continental's for Europe and pick up some more mixed tread Marathon's for this one.
Foldable tires are easier to ship and carry than wire bead tires, with no real benefit of wire beads.
As far as the chain. If it is dry, it may well last the whole trip. If you hit a lot of rain, you could wear out a couple of chains.
As in a couple of links or a couple of whole chains?
Like the tires, have a replacement plan. Most quality bike shops should carry the spares. Or, if you know where you're heading call ahead.
Heck, you could also wear the brake pads a bit depending on your riding style, but they won't leave you dead beside the road unless you really neglect your maintenance.
I'm sure that the GDMBT is going to a number on my rear brakes. Maybe I can pick up a new pair in MT. I've heard about "salmon" brakes.
Did you discuss where you're staying? There are likely a few BF members what would hold supplies until you pass through, or give you recommendations of places to shop when you come to town. And, may even loan you a couch for a night.
I plan to mostly wild camp due to the remoteness of my path and budget restraints. However, established camping in some of the National parks I would like to explore is going to happen without hesitation. I have also created accounts on Warmshowers, Couchsurfing, and BeWelcome and plan to fill in some gaps with hosts from these sites. As for BF and CGOAB members, I've never thought about that, but it sounds like a great time. If any of you who live along this route would like to host me I would be forever grateful. Let me know and I'll try to give you an accurate time table.