Conditioned crawlspace

I just purchased a home built in 1978 in Columbus, OH. Half of the house sets on a crawlspace and the other half on a full basement. The floor joists above the crawlspace are well insulated with kraft backed fiberglass. There is no vapor barrier on the floor/ground or on the walls. The walls are also uninsulated. The crawlspace is conditioned with a large HVAC duct with no damper. The access to the crawlspace is an unsealed entry from the basement. The crawl space is surprisingly dry with no evidence of mold or water stains. When I originally looked at the house the home inspector recommended installing a ground vapor barrier and un-backed fiberglass insulation on the walls. I asked about foam insulation board and he pointed out in Ohio it would need to be foiled back to meet fire rating codes. Looking at Building Science.com I see that there may be some issue with foil backed foam insulation trapping water against the wall and almost all sites say un-backed fiberglass may be an issue due to moisture absorption. At this point I'm thinking about just installing a ground vapor barrier and extending it a foot up the walls on all sides. Does anyone have a suggestion on what would be the best practice for treating this space to ensure it stays dry while maximizing energy efficiency?