My impression of winter rides on the Springwater is how incredibly DARK it is. I don't feel or see the human fear factor so much, but I certainly appreciate it. Its like solo backpacking when I have greater fear of people than the wildlife. That being said, I agree with AO that critters are more troublesome. Racoons tend to skidaddle, 'possums don't. Cats are a crapshoot what they are going to do.
Lights are a dilemma because you need enough to see, but they can blind oncoming cyclists on the narrow path. I remember a regular on-coming morning cyclist when the 205 path was still open who left me disoriented every time. If you use those blinding lights, please point them down at the path/road and if you have them mounted on your helmet, please divert your gaze away from me when we approach.
I've also wondered if there's some reflector technology that would be added to the edges (not middle) of these dark paths. They use them in the streets. Some blue reflectors could easily keep us on the trail and maybe dissolve some sense of the deep isolation of the dark. I would like to suggest it to Tri-met as they rebuild the 205 path, but sure who to direct it to.