I've navigated a couple of these on a narrowboat. Its surprising how small the chink of light remains even when you're quite close to exiting. In my case it was disorientating as well. I kept being drawn into one side or the other despite how easy it seems in theory to steer a middle course with the boat's headlight.
I've legged one as well. All part of the fun at the Black Country Museum. A great day out with great characters. I even found a Blackcountryman who was one of the guides who could converse with me in the Aberdeenshire dialect. Previously he'd been a coach driver for trips to Aberdeen and Royal Deeside for over 30 years.