So, markmadras has made a very good solution with a pulley (2744 ), but this level had a secret door of which rob has very well taken advantage by swing.
A swing was the most logical way to do this. It should be possible to do it a lot cheaper with a rope+cloth swing with only a few metal bars close to the anchorpoint. I stopped tweaking that solution because tracking doesn't work outside the level. After every minor tweak I had to zoom and pan to watch and zoom and pan again to tweak some more. I gave up after an hour of tweaking