As a follow up, here is a zip with a small C# tool that allows you to open a Unity window at any resolution (up to 4096×4096 in our testing), including resolutions spanning multiple monitors.  Multiple monitor support is not currently supported by the Windows native viewer, and is necessary for environments like our dome.

Just fire up the executable (LaunchFS.exe), click the ? button to browse for the appropriate .unity3d file.  The app will create the .html file to launch your application with the appropriate settings.

Give it a try, feel free to send suggestions.

Notes:

• Executable is in the bin/x86/Release directory
• Max resolution is 4096×4096
• Requires the .Net runtime 3.5 SP1 available from Microsoft.