There's ways to beat it without the nurse, but they all involve forgetting about the fallacy of 'classes' and adapting to the boss fight's requirements.
To minimize damage done to you, full beetle (defensive) armor, Frostspark boots, steampunk wings (or any other wings) and full Warding accessories. To deal damage to it, forget about 1.2 endgame weapons - while you can beat the ML with them, it will be much harder, and you're looking to simplify things here. You can craft lunar tier weapons even before defeating the four pillars - go to where you placed the Ancient Manipulator after killing one of the pillars, see what weapons you can craft with its drops. You'll notice murdering the next pillar with it will be much easier. If you want, check each pillar's weapons once they kill them, but here's the thing: Weapons of all 'classes' crafted with pillar drops are equally good when it comes to beating the Moon Lord.
If all that isn't enough, you can use the "teleport to nurse" trick, or what I did to farm the ML once I had beaten him a few times (farming gets tedious.) Flatten your world as much as possible, at least enough to be able to run from one side of the map to the other without stopping. Place campfires and heart lanterns next to each other (a combo known as "camplanterns" usually) and then keep placing them along your world. With a bit of work you can make it so you can just run shooting back at the boss, and being constantly healed by the camplanterns - if you reach a border of the world before the fight's over, just turn around and run the other way.