I will be attempting to port this mod over the course of this week, hopefully done by Friday or so. Although it would be possible to make a direct port, there are a number of 0.9.9.1 necessities that could very well be improved upon, given the latest capabilities of modding. Of significant importance is getting grenades to work "as intended" and updating the enemy AI to 0.9.9.4 standards, so this will end up taking longer than the other ports.
EDIT: Just an update, I haven't finished completing Metal Gear RL. However, a lot of work has gone into making the mod play in a far more stealth-based manner, so I hope you will be pleasantly surprised when I'm able to post it. (Figuring out how AI objects work is a bit of a pain, and there are a LOT of subfunctions regarding their various states.)
EDIT2: At this time MGRL is very nearly ported, there are just some final tests necessary to make sure it's bug-free regarding the AI and whatnot. Expect a very unique DRL experience! (Note that the game won't necessarily be balanced: I leave it up to Simon-v to tweak stats.)