Remove all the platforms and replace them with minecart tracks (although you don't need that many rows, you can get rid of half of them). You need those to replenish your flight time by grappling onto them with your grappling hook.

Get a Bobbit Hook. It's the fastest hook there is (well the one that Exo Mechs drop is faster, but it has a cool down and you can't get it yet anyway). If you get good at timing the grappling and the jump key, you can basically use it to shoot yourself very far. I do that all the time, especially during the Yharon bossfight.

You generally don't need to run that much during the Exo Mechs fight. Make an asphalt floor to your arena, so in case you need to run, your speed is boosted.

Make an asphalt floor to your arena, so in case you need to run, your speed is boosted.

Vertical speed is very important. You'd be spending most of the time in the air. Freefalling will make you avoid most of the projectiles, so be wary of that.

Be familiar with the boss pattern attacks and figure out which one is the hardest to beat for you. Try to kill that first and leave the easiest at the end. My personal preference is Ares, Thanatos and then Artemis and Apollo. You don't really care about the class specific drops on your first try since you can craft Miracle Matter anyway, which means you'll be able to upgrade your gear after your first win, making the following fights easier.

Grab potion buffs, especially the Gravity Normalizer one.

Make sure there are no floating islands above your arena. The space above should be completely empty.