AR in a dark environment

The experience I want to create needs to be in a dark environment. However, when I turn off the lights vuforia loses the anchor and the previously placed object disappears. My question is, how can I make a ground plane experience in the dark? Or better yet...how can I make vuforia not wipe everything from the screen when it loses the anchor? I understand that it needs light to place an anchor, but can't I somehow tell vuforia to keep everything as it is if it loses it? In fact, I should only ever need to have the lights on once, to find an anchor point and place the object, then once the object is placed vuforia should just know where it placed even if the anchor is lost, because it should be saved somewhere.