Ive been speedrunning 0-1 and i cannot for the life of me clip under the exit door, any tips to make it easier to do?

Im rubbish at doing the exit trigger bit when doing 0-1 and a friend told me to do it on violent and use the sharpshooter to instakill maurice. Ive only been able to do it once and cannot do it again, any tips to be able to do it easily?