Damn, yes they are not good. I remember being stood in a police station at 13 with bright red ligature marks around my neck from a failed attempt.
I imagine some padding might help, but you're putting a lot of pressure on your neck so I am not sure you can completely get rid of them and still apply enough pressure to the correct places. They would fade in time though, so if you failed then hopefully by the morning they would be faded/fading and easier to explain away. If you did it on a Friday night too you could hide away all weekend until they were gone?