I finally got around to implementing binning and subframing. To try it out, do:
git clone github.com/bgilsrud/indi-3rdparty.git
cd indi-3rdparty
git checkout ssg3_updates

Then you can build the drive like you normally would. I don't have one of these cameras, so I can only simulate how I think it should behave and I was able to see the USB sequences that I was expecting. I think the most useful test would be to take a recognizable image with binning enabled...there's a good chance that the frame will be reassembled incorrectly. The code will still attempt to deinterlace the downloaded image, which I'm thinking is not correct when binning is enabled.