I would personally, choose a mix of "A MAD World" and "Project Nevada".
Then put the game on Hardcore mode.
They usually improve immersion, if you add a ENB, preferably Dynamo, Nevada skies, 4K textures and a proper GPU. A last thing i need for this is a VR mod, or something like that.
If you really want difficulty, trying playing DUST with the JSawyer mod and A MAD World.
You'll regret it, but it's more of a personal opinion and how you look at it.