Good Morning, Barry,
One sheet of film can provide lots of information. Do a test shot in the same manner you would make an exposure test when printing, that is, a stepped exposure. When you pull the dark slide, don't completely remove it; leave a half or three-quarter-inch portion in the holder. It's easy to mark the slide so that it is far enough out for exposure of the whole sheet of film but still in the holder. Make one exposure, then push the dark slide in an inch or so; make a second exposure and push the slide in another inch; then repeat a third and fourth time. Yes, it's probably impossible to do this without a tiny bit of camera movement from one exposure to the next, but with a solidly locked-up tripod, it shouldn't be a problem. You're only doing a test, after all, so slight movement won't affect the usability of the results very much. Process the sheet, preferably using a very soft-working developer. I'd start with T-Max 100 or Acros at an exposure of 20-30 seconds at ƒ16, with subsequent exposures adding about the same amount of time each. Keep notes! If you're doing a twilight shot, for example, note the time after local sunset. When you return for the "keeper" shots, you can always make minor adjustments for slightly different conditions. When I do night exposures, I usually shoot four sheets (because that's the way I process and contact) with slightly different exposures centered on whatever I think is the "correct" exposure.
I agree with the previous comments about the limited usefulness of a light meter; experience and note-taking are more than adequate. Fortunately too, the eye and brain seem to make generous allowances for varying renditions of night scenes.