Here's another personal opinion, not an authoritative answer. I don't think there's anything wrong with identifying the burial location of your ancestors, but if you think there could be an issue about it, you could be a little bit vague about the specific location, or else add a caveat saying that the location is on private property and cannot be accessed without the permission of the property owner. Or, as you suggest, you could ask the owner for permission to publicize the location or allow blanket access.
Editorial comment: I know of a couple of similar burial grounds near my childhood home. As a rule, they are poorly maintained, or not maintained at all, and are areas with falling-down tombstones and overgrown with weeds. In each case it seems the current owner respects it as a burial ground, but is not a descendant and doesn't feel any responsibility, so it has basically become a no-man's land. If you are in the area, or have a willing family member, and would be willing to do a little cleanup, you might find the property owner to be very cooperative.