After much testing I've finally found possibly the most consistent setup for the to own the skies skip. It takes a bit longer to set up than the usual one, but it's maybe 50-75% consistent. Also, because the sonic detonators are on the ground already, to retry you just reload and move to the side to trigger the spawn, so a reload only costs 2-3s. I'm sure there are ways this can still be optimized to perform it more quickly or make it more consistent.

EDIT: I've found doing it from here with 4 grenades, aiming at the same spot, is actually more consistent. I did it 8-10 times and it didn't work only once, and its a bit faster https://imgur.com/QM0kO2r

It works well, although it costs 4-5 grenades... Fortunately there is pickup in the next level. Also sometimes the door appears knocked down from below, but still blocks the way, and you can only see it once you're on 2nd floor

Yea, i think it could use some optimization to improve consistency still so that doesn't happen