Are you looking for a static overlay, or something that will change dynamically based on what the driver is doing or the camera is seeing? If you use the smart dashboard, it's easy to add a static image that you can position over the camera feed. I'm unfamiliar with NI Vision, our team used OpenCV in a custom camera widget on the smart dashboard for dynamic overlays (
https://github.com/Mercury1089/MercuryWidget here's an example custom camera widget).