Resolution when connecting to a headless Mac Mini

My setup is as follows: 1. Mac Mini 2012 with a dummy video adapter with latest OSX. 2. Retina Macbook Pro 13-inch, Early 2015 running the default OSX VNC client with the latest OSX. 3. Display Menu to switch resolutions. My problem is that I'm not able to get the right resolution such that it fills up the entire Retina Macbook Pro display. Ideally I would have liked 1280x800 or equivalent higher. This way it would fill up the entire screen (though it would be scaled since Retina has a higher resolution, which is fine). However the only resolution options I see are: My question is that do these options depend on the dummy video adapter? If so, is there a recommended video adapter to achieve such a setup?