Chopping tempered glass isn't hard to do. Use lots of duct tape. Cut the tape at your desired new dimension. Sandblast it slowly and it will cut it nicely right where you want it and leave a nice soft edge. Works well. Try an old window first to get the hang of it.
Your door glass probably won't need to be cut at all since it has vertical, parallel posts. It will still roll up, just fewer turns!
The windshield and vent windows can be cut the same way as the back glass too.