You can tint the vision gray, but that is really just putting a ~35% transparent gray flood over the vision. It is not actually tinting anything. I.e. it is not changing any color values. To do so would require a different rendering method for this feature—a filter rather than an overlay. This is the second time I have seen this brought up recently, so it's probably worth a suggestion. As a technical explanation* of what's going on: Light and vision don't actually illuminate anything. You place a map down, and dynamic lighting automatically darkens the image by the desired amount. "Light" and "Vision" are just masks that let you look through the darkness at the normal map underneath. When you turn on explorer Mode, the "hidden areas" are just a another layer that is basically a grayscale version of the map. I don't know if this is done with a filter (in which case grayscale vision would be theoretically possible, though I have no idea how difficult), or if it is a generated image with a dynamic alpha channel (transparency mask). *My understanding of it, anyway.
