One way of doing Early Master Sword in TWWHD is by spawning on layer 8 in the overworld. This can be done by skipping the gossip stone on your first visit to Forsaken Fortress and then then coming back a second time, using the pirate ship, to reclaim the gossip stone and beat Forsaken Fortress a second time. Doing this causes Link to spawn on layer 8 in the overworld which is a result of the game expecting the cutscene where Link and the King of Red Lions talk for the first time. This cutscene does not play but the game still sets the layer for the cutscene anyway. On layer 8, the door blocking entrance to the Helmaroc Boss Room in Forsaken Fortress does not exist.
From the second highest platform on Forest Haven it is possible to perform an incredibly precise Item Slide aimed at the Forsaken Fortress top level loading zone and get behind the door before the collision of the island loads.