One note: In Discord, I mentioned opening up the roof of the rail that is exposed to actual biomes such as crimson or warped forests. I replaced the stairs in these parts with cyan glass so we can see the ambient environment. Feel free to apply to other rails!
Hey, so, small update; I've convinced myself getting rid of the ice road in favor of a soul soil path (to travel along it with soul speed III) is going to be a better idea for the nether tunnel system in the long run (and maybe even invest in speed beacons all along the tunnels in the long run?), and so, I have changed up the designs a bit. These tunnels sacrifice boat travel to optimize soul speed and elytra travel through the tunnels.
Warped Tunnel (North)
Soulsand Tunnel (East)
Crimson Tunnel (South)
Delta Tunnel (West)
Also note that I swapped the east and west tunnel around, since there is a basalt delta immediately west of spawn, so that seemed more fitting. There's soul soil under all the carpets.
New Materials Needed (500 blocks in every direction): - 152 stacks of Soul Soil - 16 stacks of Brown Wool - 16 stacks of Red Wool - 16 stacks of Cyan Wool - 16 stacks of Black Wool - 4 stacks of Lanterns - 4 stacks of Soul Lanterns - 40 stacks of Crimston Stem - 40 stacks of Warped Stem - 28 stacks of Basalt - 28 stacks of Bone Blocks - 59 stacks of Nether Wart Blocks - 59 stacks of Warped Wart Blocks - 59 stacks of Gilded Blackstone - 39 stacks of Polished Blackstone Bricks - 39 stacks of Smooth Quartz Blocks
As far as I know, respawning the end dragon doesn't do much damage to the island. The only issue is that one of the obsidian pillars will regenerate, straight through the tunnel from the obsidian spawn platform to the exit portal. So just make sure to open that up again after defeating the dragon