Here's my opinion, and in my experience it works quite well in game.
You do NOT need three engineers. You need two standard non-buff engineers (mallet, spanner, extinguisher), and a gunner or buff engineer.
Gun lay out should favor long-range attacks over close quarters combat. Artemis lower deck, both sides. Mercury top captain's-gun. Captain can use the 'trick' to mount the top gun without getting too far from the helm, or the gunner/buffer can use it exclusively. Your choice of close-range weapons on the middle deck. Carronades recommended.
One engineer is totally dedicated to each side; Artemis, engine, and hull/balloon. They NEVER leave their "hallway". Gunner/buffer mid deck, handling the snipe during maneuvers and the close-range guns if an enemy gets too close. Gunner/buffer only has to worry about repairing his guns, and the main engine.
Pilot should equip tar barrel to compensate for the very large blind spot behind the ship. Possibly kerosene, chute vent/hydrogen to complement the ships vertical acceleration, or phoenix claw to keep the enemies in weapon's arc. Burst rounds on artemis for the extra ammo and the AOE increase for accessibility of disable/kill shots. Gunner/Buffer ammo depends on weapons equipped.
Park the ship at mid-long range, that way there should be NO repairs for the balloon/hull "hall"-engineers to worry about. Snipe, snipe, snipe. The two artemis on left and right low should be able to overlap arc at forward facing, and a good deal of side-front. You should be far enough from the engagement that the merc can easily strip armor and disable guns. Artemis disables everything else, and then goes in for the kill when hull drops.
If an enemy gets too close, you have a close range weapon on either side to facilitate a quick getaway, or entirely disable the foe. Carronades, combined with the mobula's climbing ability makes for a quick escape, and fire weapons do well to dissuade the enemy from continuing their attack. During close-range encounters, the engineers will most likely be worrying about hull/balloon depending on the enemies location (balloon low, hull high or on your six). The lack of vertical arc, and slow turn speed of the artemis will not be an issue, as no one will be firing these guns during a direct engagement.
When using this setup, by avoiding all close contact with the enemies, there should be minimal repairs needed. During heavy repairs, each player has a very distinct and defined role, and there should be no real problem getting to components that are, in fact, quite far from one another.
