Phenix Nocturne's guide works and you can AFK it, its just slow
a much faster way to 1000 deaths:
load up level 16
rubber band your controller to go left
roughly 1 death every 2 seconds
if somehow starting with 0 deaths, you can get all 1000 in 35-40 minutes this way.
credit for this goes to a youtuber who goes by the name Bjørn Nilssen
here's his video: