I ran this recently. I made a DL "circle" to keep people from seeing in. Once they entered it, I just turned off their sight (easy with Pro, not as much with plus, unfortunately), and had them describe the direction and distance they wanted to move. I was very forgiving about obstacles, just figuring they were feeling their way along if they ran into something that required navigating around. I asked them to move at half speed, which made the descriptions shorter. They could move at normal rate, but then I gave dex rolls and minor damage or movement dings if they ran into something. It's amazing how much pitch darkness becomes debilitating if the players don't have "god mode" to show them their map position. If you don't want to fiddle with their sight, leave the token at the point where it entered. This way they still have a general idea of the greater area. Use any NC token as a marker for the DM to track their progress inside the DL circle. (remember to draw your circle as a multisided polygon—DL abhors a curve).