Okay, here's where I'm at with the bike.
I spent the better part of six hours (not joking) in the Yamaha dealer's parking lot taking apart my bike. I did feel kinda bad-ass; people were dropping off their bikes for servicing by the factory mechanics, for incredibly minor stuff like oil changes and stuff, and there I am in the parking lot performing the motorcycle equivalent of hip surgery with basic hand tools and a leatherman.
Anyway. I got the crank case cover off, and this is what I found. The crankcase cover itself:
Not great, but I think it could be worse. I don't know if that can be welded, as it's almost shattered, but I might be able to tap it back together and JB-weld it. It's worth a shot, at least, I'll have to wait until Monday to take it to a welding shop and see what they thing.
As for the crankcase itself
Some small cracks, but I don't think they matter. They don't go to the outside and the hole isn't so badly mishapen that it won't accept another bolt.
I'm camped in an R/V park next to the Yamaha dealer. They have free wi-fi, which is how I'm writing this. Actually, the story behind how I arranged to stay in this place is kinda funny, but I'll save that for another time.
I'll be here until Wednesday at MINIMUM. If I can get this thing welded, it's still going to take a couple days to get a new gasket in. But on the upside, I'll have internet until then, so maybe I'll get around to uploading more pictures and catching up on the trip report.