Some couples are great at camping. Without argument, they know who carries the water, when to poke the fire, how to assemble the tent. From the outside, it looks seamlessly easy — all the more miraculous when each partner has a strong personality and a distinct idea of how their excursion should go. Susan Smereka and Kevin Donegan are surely one of those couples, although their tents, on view as part of “Fluid Dynamics2” at the Julian Scott Memorial Gallery in Johnson, did end up upside down and on the ceiling.