Force the resolution on a headless mac mini server

I have a Mac Mini server running Mavericks. It has no monitor connected. I use Remote Desktop on my laptop (also running Mavericks) for I/O to my server. When I use Remote Desktop and go Full Screen I get a 1280x1024 screen sitting in my 1680x1050 screen. Is there any way to force the client (Mac Mini) to use a setting of 1680x1050 so I get a real full screen? I tried holding down the option key while clicking on Scaled in Display -> System preferences. All I see is a new button in the bottom right that says detect displays. Clicking on it does nothing. The only resolution shown is 1280x1024. My Mac Mini Server is a late 2009 with an Nvidia GeForce 9400 graphics card.