I think getting the in game progress to say 100% is the easiest and most accurate way to define 100%

Another Category could be All Suits/All Upgrades which would mean Golding every challenge to buy the mods, suits and gadget upgrades.

100% should be just getting the in-game progress to say 100% it is harder to track trophy progress.

I don't see enough difference between difficulty settings to justify a new category but challenge IL's might be cool (For Taskmaster missions, Base clears and I guess Research Missions?)

Regarding Fast Travel I think the game has enough swinging even with fast travel to satisfy everyone.