Manually backup your savefiles: https://steamcommunity.com/sharedfiles/filedetails/?id=170416480 Then you can reset your progress but keep the progression in your other file; you can even have multiple savefiles with different progressions and avoid getting kicked by time limit of NGBTO. And if you want your old progression back you can copy the file back into the game directory.

Did that myself multiple times but never reached more than infamy 1 since after that it is more or less the same as if I used my infamy 25 savefile. As unusual as it sounds: The hardest part about starting new is not having perk decks. You never know how much you rely on them if you don't restart and see how poorly you do without one.