I'm day 54 or 55 in my current hardcore run. Killed Eikthyr on day 7, killed Elder on day 35. Since then I've been spending a lot of time in / around the base, mining and smelting, gardening, etc. No idea where Bonemass is at, and, thus far, I've only discovered 2 or 3 swamp biomes and they're a lengthy sail away.

I'm kinda worried about the swamps if I'm being honest. I think that's where I'll end up dying, but we'll see.