I run a nice cree flashlight from ACE hardware, cost, about $30. has 4 different modes. I use the twofish lockblocks on 2 different bikes, they work perfectly. A radbot 1000 or something on the back. I've got 2000 miles on each, never had a problem. My system works well enough in pitch dark- bright enough to ride by, good rear protection. About $100 out the door. It's easy (and fun) to overthink it- lots of options out there, but really, it's not that hard. Now I'll be shouted at by light enthusiasts.