bike traveler from Austin, Texas on 9/3/2019 9:26:26 AM:
I went through all the tunnels without any lights.  That said, you may be more comfortable going through Paw Paw tunnel if you have a light.  It's over half a mile long and is completely dark inside.  (You'll want to walk your bike throught Paw Paw regardless of whether you have a light.)