I have had thoughts of how a hotline Miami RP would work, but it'll be difficult to both grasp that appeal and merge it into the original story design, all while avoiding having people turn it into a gore fest of an RP.

It's because the game is so dependant on that core game design that the story is really there to link it together and create a lil mystery. I'm interested, but not confident that the world will allow for it unless you make it an alternate universe (eg: both jacket and helmet died during their fight, thus making hm2 a completely different story.)