1) Hiding bodies – Like if you can get a kill at just the right moment the body can't be found. For example if they walk close to a vent you are in you can drag them inside to their doom, or if they are emptying the garbage you can just push them in and flush them into space.
Setting traps – Setting certain task stations to backfire and kill whoever is trying to do them.
Obviously these could potentially shift the balance of the game even more in favour of the imposters but they could balance this out by slowing down the kill animations for stealth kills making it more likely you will get caught and by making it obvious when somebody is setting a trap so they can only safely do it when they are alone. I would also suggest limiting the number of traps that can be used in any given game so that the imp has to use them strategically rather than just leaving them everywhere.
Of course the game should retain the option to just turn these features off for people who want a more standard experience. But it would be cool to see how people adapt their strategies when playing as crewmembers to counter such potential deaths. For example if you have a visual task you may no longer want to announce it in chat to show your innocence if it reveals to the imposter where they could place a trap to kill you. Or you may be more wary of doing certain tasks in view of others, like if the imposter sees you filling up at the fuel can he will know at some point you will need to go to the engines so could leave a trap for you there, best to wait to do certain tasks until you are totally alone.