Sorry about the belated answer, I do, occasionally. But currently I am on hiatus because I am studying programming in real life.

I know this is off topic, but do you do custom mod request?

Yes, this, paired with Re_Kenshi replaces the vanilla ragdoll with a ragdoll I made. The new ragdoll has rigid forearms so they do not flap. Indicentally the new rag also seems to be lighter for the engine to render, so also slight boost to performance. But yeah, this is a complimentary mod for riding. It is a separate mod, cause it is also a modder's source for other vehicle makers etc.

Wait what does this do ? It fixes the arms flapping when riding ?

The issue with Re_Kenshi is now fixed with the latest update :)