I feel like swapping reach with lag backtrack would be a fair compromise between detectability and basic features. Assuming it’s a smooth backtrack and not one of the ones that spike your ping every time you get within 3 blocks of a player it’ll be a while before it’s detected on a wide scale.
Leave the window open. From what I remember that’s the window that renders external visuals. Normally it gets hidden automatically but sometimes it doesn’t.
Depends on if they block / commands. If not you can probably go through all the anticheats and see if the / command works for it. You can also try checking transactions.