Mobs don't spawn in your walls if you have bonfires and workbenches setup. Still super grindy and probably always will be, just stick to mods to remedy that.

Mistlands is on the PTR currently, and it's very grindy, more so than previous biomes, and much more difficult. I'd say it's worth checking out. Might be better waiting for full release of Mistlands vs grinding it out on the PTR, cause who knows what bugs/issues may pop up that will be fixed in the next couple weeks.