Here's what I found with a few minutes of testing:
If there is a way for the ukulele to be grabbed OOB you could be able to warp back inbounds with a save/load. This could be made possible because there is a wedding cake about two or three rooms down on the left of the 4th floor from where you begin Night Resort (you'll need the master key from the bellhop again as I don't think you carry the one from the previous Kai Tak level). So what you would do is activate the cake in the room, find a way to grab the ukulele, then save/load and you can warp just outside the room. I didn't fully test this sequence but save/loads did warp me outside the room from inside it.
I've also considered maybe you could use another item that creates a hitbox as an alternative to the ukulele, however I did not have any success with that yet. Below the other pool behind the hotel (one with the bar) there is a can of spray cheese OOB that I tried on the pig, but it did not work. I tried searching for other items, but nothing I found had a swinging animation (hotel key, metal detector). There was a ukulele hanging on the wall in your original hotel room but I couldn't pick that up :(
In summary, it's going to take quite a bit of digging to skip the long Night Resort cutscene if there even is a way, and getting the OOB ukulele seems like the only possibility right now. Reminder I did not do an exhaustive search of the level, although I did some coverage including hotel rooms on various floors. This was what I found for a few minutes of investigating and I could do more after I'm done with work in a few hours.
The other rooms in the hotel are actually all the same room. The game puts the spy van in the room the first time you enter it. Then the randy guy followed by the cake. Nothing else will appear in the room after that so dont worry about going through all of the hotel doors. Another note the cake inside the room cannot be warped to unfortunately, save loading will warp you outside of the room while you are inside it but will not if you are already outside the room :(
There are however three other cakes present on the map that can be easily warped to so this isnt too much of a concern.
Okay So here's what we know for a possible skip:
we can get out of bounds. It's possible to grab the ukulele BUT we need a way to do it without noclip. we can warp back inbounds with either save/load or cake warp. There doesn't seem to be another weapon to attack the mechanical boar, The sword for the Fruit ninja type game doesn't work.
