Crazy. I checked the fuse earlier, but as soon as I posted, I thought I should probably check it again. YEP, that's it. I was just assuming it couldn't be b/c I wasn't even going anywhere, but I found out what blew it. It WAS the back brake electrical contact. the contact housing itself is busted, so it would be hanging loose or off, causing it to arc--bye-bye fuse.
Unfortunately I realized it after it blew the spare fuse. Gorilla taped the housing, picking up more fuses tomorrow, then see if I can actually get some fun in on this puppy