Would it be possible to exploit the magnesis rune to carry you past the void warp to a warpable spot then warp back to that spot?

Every spot outside plateau and a bit of water is covered by void trigger no matter where you go, even if you warped there you would instantly void back. Only the paraglider will take away the trigger, there is no other way to escape plateau.

Zoro>>>>>>

Yes, skipping the plateau seems impossible but, what if (a big if) you used a stasis launch to the Calamity Ganon fight? Is it possible that the cutscenes could eliminate the void out? Still, it would just be a cool glitch to do and probably not useful to use since you need a cooking pot to make the power elixir and all that. :/

Not to mention the weapons needed to even be able to last half the fight.

Sadly, warping to Calamity Ganon fight from the plateau has been tried with hacks, and still voids out. I believe it was in a video from "Gymnast86" - a popular Wind Waker streamer - which also included many other details about the void out.

Basically the only chance we have at plateau skip is tricking the game into giving us the paraglider early

I don't remember that mentioned in his video, weird. Well, maybe someone will find a glitch to skip the great plateau someday :/

I may be mistaken, I've watched a few videos on the topic now... My apologies!

This has been bugging me but why does that one patch of water and land both avoid the void trigger? I'm really confused why that works and no where else (so far) works

Lake Hylia for whatever reason is within reach. There is now void floor above it. Maybe cause Nintendo wanted it to be all nice and clear there, so it looks more impressive. If you leave a small cube around Lake Hylia, you die though, so its not useful.

Also yes, warping to Calamity or even Beast Ganon with Hacks will still void you out and put you back onto the Plateau.