Earlier on in my auto detailing adventures I had done many night time wash, wax and even paint corrections. Nothing like the shock and embarrassment of only thinking you've achieved stellar results, just to have the owner wake up in the morning, walk out to his sun emblazoned car to see the holograms that you only thought you removed the night before.
There is definitely a needed (working blind) technique when working at night with not the best lighting. As far as wash and wax only, it's pretty straight forward as long as you use your sight as well as your memory to know exactly where you have washed and waxed and where you haven't washed and waxed when working in poor lighting. It's easy to miss spots while wiping off wax and or sealant when working in the dark. I'd suggest a clear wipe on walk away sealant such as UPGP or Opti-Seal or a simple (clear) liquid spray wax such as DG-AW or OCW to minimize the tendency of missed spots. Leaving white dried wax in the cracks or on trim does wonders for your negative word of mouth.
Just a few suggestions out of my own experience.