Moin,
the video is amazing. This will be one of the few mods I´m going to have installed on my rig.
As for the widescreen mod, there is nothing you can do to make it not compatible.
The viewport alterations only affect the 2D views (periscope, uzo, binocs). Whether the 3d structure appears stretched or well proportioned depends on the cameras aperture angle (cameras.dat). So, those who are able to run WS now (ATI vs Nvidia) will be able to run it with your mod enabled too.
Regards,
DD