I feel that the spire has a lot of utility, which people overlook. If you shoot something like the hwacha, the gunner can hop off of the gun during the reload and run to the bottom-left gun, and have the top-front gun join its firing in a bifecta. On a sniper medium weapon, the gunner could also opt for the closer-ranged left bifecta when the opportunity arises. Likewise, the two top guns can do their own bifecta. Deciding what gun goes where, and what works the best together, is definitely the key to making the Spire work. There's only so much that an engineer can do beyond buffing the hull, so its up to the top and bottom gunners to make it work.
My build is top-front Artemis, top-right Artemis(for the right bifecta disable), bottom-right Gat(For left bifecta damage), Lumberjack(for harass at all other ranges).