So the trick is easy and very safe. Here's a setup video.

Get to the gnome screen.

Go DOWN as far as you can so you're hitting the rock.

Move LEFT to the river screen.

On any of the frames where the screen is fully black, change to holding DOWN RIGHT. You MUST do this before any fraction of the screen loads in

Then you have infinite time to press 1 and transition back to the gnome. Once on the gnome screen, press RIGHT. Boom, Gnome Skip.

So basically you have always got an 11 frame window to achieve this. You can also PAUSE while the screen is black to be super safe if you want to.