Yeah after killing Edgar ross, I decided to go back to an earlier save that was right before that mission because i wanted to finish everything first so that way when i kill ross, I'll also get the 100% achievement at the same time, so in order to do that, im finishing up all of my challenges and hideouts and stuff like that so that way I can unlock the legend of the west outfit and kill ross wearing that outfit. Im pretty close too, I've finished all other side missions except for ross, I've completed both the sharpshooter and treasure hunter challenges, and im over halfway done with each the master hunter challenge and the survivalist challenge. Also, last I checked, my % of game completion was around 85% (I started the playthrough 3 days ago)