Yeah I have the same issue where the 4V conversion is good most of the time, but for certain content, forcing it to just display original L/R Stereo looks best.
I posted (early this morning) a guide for streaming SBS 3D and 2x2 4V video content from your PC to your Lume Pad / Hydrogen 1: Guide: How to stream your own 3D-SBS or 2x2-4V videos from your PC to Lume Pad using Jellyfin & MPV-4V (Works with RH1 too)
Check it out and let me know if you need any guidance setting it up. It’s like you suggest tho, rip the Blu-Rays, serve them using Jellyfin, and then view them on device with Jellyfin configured to use my special 4V fork of MPV Player
If you find it helpful, there’s donation links in the release notes. 