If you really want to use the bow, do the tree method mentioned above.

I generally build a wall around the entrance to a crypt, not to trap bonemass, but to provide a safe space. I build the wall the same height as the crypt, and he doesn't get in. A bonfire on top with a couple of roof sections over the entrance provides rested state.

Good armor, good food, poison protection, and a mace will take him down pretty fast.

I also built a house over the skull once (actually several times). It was pretty large with walls 2 6x2 blocks high, with a tall roof and a balcony over the skull. Long story short, I didn't build it to trap him, but he got trapped on the balcony and was helpless. So I beat him to death with a mace.