I recently replayed this highly underrated game and modded it along the way until it did things the way I wanted it. In general it makes most bodies stay, scorch marks stay as well while glow effects fade correctly. Same goes for acid and slime from hidergun and crab grenade. I created permanent stains for these after the glow fades. This mod is built on top of SikkMod lite 1.2 for Prey, which I included in the download. It should be working without it as well though.
Oh this looks like fun. I'll get this and keep it for my next playthrough in the future. Thanks for your work.