How long are these tunnels and are they open to cars? Are you more worried with being seen than you seeing?

A Cateye EL530 with a Cateye LD1000 tailight (because of the good side views) might be all you really need. Maybe have a few reflective arm bands if you're worried about being seen.

If you are thinking at all about night riding, I'd consider the Nite Rider MiNewt, single or double headlamp. Incredible amount of light for not much weight. If I didn't already have the EL530 for the odd times like you describe, I'd get the MiNewt. It is definitely more expensive but far more versatile.