In the dark, floating or intermediate lines are your best bet. Wade fishing for stripers at night during this time of year is one of the few times I prefer a floating line. Even slow-sinking lines, like intermediates, will allow your flies to hang up when retrieved slowly, and I strongly advise you to reduce your retrieve to a maddeningly slow pace, even to an inch per second. Fish feed slowly now, so give them a chance at your fly. Sometimes the take is gentle, just a feeling of weight or a tic, but more often, my experience has been that strikes come very hard. Bass will often track a fly slowly, swim up and mouth it with a violent grab.
Two things will enhance your offerings presented in this manner. First, a two-hand, hand-over-hand retrieve allows your fly to swim steadily, without the intermittent stop-and-go action of a one-hand strip. Second, use bulky flies like the Popovics Siliclone, easily my first choice for slow nighttime probing. Flies like this wake just at the surface and push water, which seems to cause pressure waves or vibrations which attract bass. Some of the most popular lures used by generations of spin and plug casters work just this way. In any case, in the situations I've been describing, I've had more success with medium-size flies, perhaps 5 or 6 inches, rather than 2- to 4-inch imitations, or large versions, say upwards of 8 inches.