OSX: Getting an accurate list of supported screen resolutions in CaptureDisplay mode?

For my cross-platform 2d computer game, I've been trying to determine how to best handle multiple resolutions with an in-game menu in Unity.

In order to support retina screens in OS X, I discovered that I need to set Mac Fullscreen Mode to CaptureDisplay in the player settings. When I do that, Screen.Resolutions reports

 640x480
 720x450
 800x600
 840x525
 1024x640
 1024x768
 1280x800
 1440x900
 1680x1050
 1920x1200
 2048x1280
 2560x1600
 2880x1800

However, when trying to set the screen to some of these resolutions (for example, 720x450), I got an error in the dev console: "Could not find requested mode."

On the other hand, in FullscreenWindow mode, the listed resolutions are

 640x480
 720x450
 800x600
 840x525
 1024x640
 1024x768
 1280x800
 1440x900
 1680x1050

I can switch to all of these resolutions, but doing so stretches the screen contents to cover the entire display rather than supporting the chosen aspect ratio with black bars like in CaptureDisplay mode, so CaptureDisplay mode seems to be a better choice than FullscreenWindow mode overall (after hacking it so that command-tab switches to windowed mode rather than blocking input).

My question: how can I get an accurate listing of available resolutions in Capture Display mode on OSX (I'm using a late 2013 Retina 15 inch Macbook pro running OS X 10.9.3, but I obviously want my game to run properly on every machine possible)?

Alternatively, what is the best way, from a user experience standpoint, to user-selectable resolutions, ideally with the ability to select the maximum resolution available - 2880x1800 in this case? Do I need to write a native plugin to do this?