The concept is reality.
I've taken the third entry of my table put out by my script found in this post. Which is 0 frame delay at the tunnel and 22 frames at the child cave. Also, I seem to defy my own expectations by spawning the fairy in slot 5, where I only output paths for a fairy in slots 0, 1, or 2 in that table.
Seriously, I just can't predict what slot that thing will appear in, and it is possible to pick a different lossless path using the same RNG/gTimer pair that spawns the fairy in a different slot. I also spent more time waiting than expected, requiring more path than I reveal from my script.
Regardless, this proof of concept by itself should save over 100 frames. Spawning a new fairy on our way out of town shouldn't be an issue with all the screen transitions. I will be looking into how feasible it is to spawn two fairies in a row and have them fly straight to our next trap (immediate 3x east travel for our west fairy). At least for the second fairy, the east fairy will always spawn in slot 7, and the west fairy in slot 5, as nothing else will be taking up our slots, so prediction will be more stable.