We have the distinction between Any% and Any% S-Rank because there are a lot of missions where you can use rank reducing equipment for an even faster time. Air Strikes and the Fulton Ballista are the two big ones. For any% missions that use those, S-Rank tends to play somewhat differently.

No Traces runs are similar to what you are referring to. We could do something like a Low Equipment % where you only use, say, 5 star equipment and below. That would eliminate a lot of the OP equipment. The thing is the boards already look pretty bloated, and for the most part between the categories we already have established a lot of new categories will wind up playing out the same. I like using weaker equipment for a bit of a challenge (And it helps newer players jump right in), but I think my point still stands. I'm open to suggestions though and personally I don't mind having more options available. I think nobody wants the boards to start looking cluttered, though.

In some of my IL runs I have used similar mods (Different female MB soldiers). As long as no game play is altered, simple character swap mods should be fine.

I also play as Big Boss instead of Venom so, that's fine as well.

I don't know if this has ever been brought up before, but I see no reason it would be banned. Current runs accept the bonus soldiers you get from a GZ save file to help boost your army, so the GZ suit should be allowed as well.