I'd say that if you've assessed that you're ok riding in the dark at that end, go for it. Also makes sense that you would want to be dealing with more difficult riding conditions at the beginning rather than at the end, tiredness is not the friend of adaptability.
You're riding a unicycle 100 miles in a day. In my mind, you went past crazy a while back, but in a good way. Now is the fun part--variations on a crazy theme.