I find having a second character blocking the character skimming around in the gap helps. This is the only trick in the run which I have not found a consistant trick for. If you look at my wr run on coop you willl find that we stand in precise positions for some of the skips. Although if you are playing solo that is not very helpful. For the tree skip I roll into a precise spot where the first character starts 'floating' and then switch to a second character to keep the first character in that position. In regards to the fish ledge grab I dont start tapping b until I am already under it.