To expand on the 3rd level timing issue - I think part of it is how long the inflation animation takes, which makes it hard to time your expansion with the gap in the guards' sight.
Viewing post in [NSFW MiniJam #19] Stealth Under Pressure comments
Thank you for playing nonetheless! This part is supposed to be challenging and to make you figure out the right moment. Otherwise, there would be no real gameplay, considering how short the game turned out. But I assure you it’s not too hard either once you get past it with a bit of trial and error.
To pass the first two guards on the third level, you may wait when the right guard returns to the left and the left guard is about to look at right. Then, by the time of your ascend, the right guard will go to the right, and the left guard will look to the left again.