Depending on world seed, you don't even need a ship to reach mistlands.

One could also find an appropriately positioned ruined "aqueduct" or whatever, and have a gjall bring it down for free iron ingots. I'm not sure if any enemy can break down the scrap armor and swords though.

As far as I can see, the only relevant "skip" you can make in progression is if you can make do without wisps, because not killing Yagluth will keep the free black metal rolling in and not replace that with insect food delivery. With thorough exploration of the world, you could easily find several dungeons and other mistlands sites without the need of wisplight.

Despite the example above, I don't think it's feasible to think about acquiring iron from mistlands unless you literally have not found a single crypt and are able to reach mistlands accidentally on foot. All the other bosses except Elder and Yagluth provide very useful Forsaken powers which shouldn't be skipped for any reason. So that only really leaves Yagluth as an outlier of sorts... Maybe Certainly in future biomes there'll be more use for his power.