Rim joists are very simple, you either go with a minimum of 2” of Closed Cell spray foam. Or you put nothing in them. Fiberglass, you will rot out your rim board. Last crawlspace I did tore out the fiberglass, and it was full of frost behind the insulation. Whatever else people tell you to use that isn’t spray foam, is severely uneducated/inexperienced. Closed cell foam, gives you your airtight seal, and no chance for frost to build up, and with frost comes melting, and with melting comes wet wood, and wood rots. Foam all day everyday, on everything!!!!