I had a portal fairly close (ca. 30-50m) to the fight with Bonemass. Died once, hopped through the portal, picked me up and was back in the fight.

But good call on getting the iron armor. I actually fought Bonemass with mostly Root armor, but lvl 4 iron greaves, lvl 3 iron mace and lvl 3 iron banded shield.

I would not engage him with a bow, as he is resistant to pierce. Only blunt works reliably. You should not have any problem with it. And you should ALWAYS have a portal close by. Not to have one is literally cutting off your life line. It is stupid not to have a portal close by. I actually also have a small base close by. So no matter what, I can go and pick myself up.