I've been trying, i dont think it's possible, but there might be something we can do in Kai Tak night as ive found a OOB clip
the ukulele you need to kill the pig is actually out of bounds right under the rear pool so if there was a way to clip oob there and grab it you could cake warp back in bounds and skip talking to the conspiracy theorist guy
Like I said, I know away to clip out of Kai Tak, but the ukulele is a little too high up to fall and grab it. (from what I've seen and found) when I get home from work ill make a video about clipping out and you guys can look for yourself
I doubt cake warping back after grabbing the ukulele will work. Remember Kai Tak Resort and Night Resort are considered 2 different levels by the game, and the game will softlock when trying to enter Kai Tak after completing the level the first time.
What you could do is create a new save file in Night Resort before heading to the pool. Optimally, I would create it probably by the elevator on the 4th floor so you load warp back there then jump off the other side to the exit. This is of course permitting grabbing the ukulele early is feasible.