If this thing is going to be stuffed in helmets or other equipment, it needs some kind of enclosure to protect the electronics from moisture and dirt. I used a material from Smooth-On called XTC-3D to finish a 3D print recently (which is what that material is designed for), and I think it may work for coating electronics too.

I tried it on a test PCB with no parts populated, since I don't want to pot the one that I'm hacking on, since I need to be able to probe traces and pads. I know that there are potting materials made specifically for electronics, but this stuff is pretty easy to get, a little bit goes a long way, so it's cheap, and we'll see if it works well.