Sorry, just now saw this. I'd recommend joining the CTM Speedrunning discord to continue the discussion.

Unfortunately there's 2 big limitations to this trick: 1) you have to play in 1.3.X or 1.4.X, and 2) you can only do it in spawn chunks or chunks extended from spawn.

I'm not sure if you were already aware of #2, but if the areas you mention aren't in spawn chunks then this would make it impossible to do it in the areas you say in Sea of Flame 2. I would have to look more into it myself, I'm not super familiar with the map.

If they are indeed in spawn chunks, then that definitely could be a timesave, although there are other timelosses associated with having to play in 1.3/1.4 instead of a version like 1.7 or 1.8 (mainly enderpearl deloads) so it's not so straightforward.

Again, please join the discord if you want to talk about it more, definitely interesting.