XPS under floor insulation/vented crawlspace?
I live in a moderate climate, in a house built over a vented crawlspace. Presently there is no floor insulation. I'm considering doing some spot insulation, in particular under a bathroom. I could put fiberglass batts between the floor joist, but I'm also considering using 2" XPS, which would also be between the floor joists. Small area, so the slightly increased installation time wouldn't be much.
Okay, or bad idea?