I just did that. I did it waaay earlier than I did my first game which was a mistake. My character is very weak and I barely had any ammo. I'm thinking "it's just a few mirelurks if I remember correctly", oh right a giant mirelurk queen at the end, which literally all the ammo I had left after clearing out the mirelurks was a sniper rifle and shotgun lol and three stimpacks. Took at least a dozen tries to kill that thing with a sniper rifle, not even a .50 cal just a regular slightly modded sniper like 42 dmg lol. Pot shot that motherfucker, run in the castle, repeat. Just one shot from its gooey spit and it kills me. I need to level up more