This (left) is my combination light bar and head/neck rest. It started as one vertical stub on each side of the mesh seat, held on with lamp mount clamps.
|A seat-edge lamp mount clamp|
The trick is that this kind of clamp doesn't need to go all the way around the bar you clamp it to, in this case the edge of a typical recumbent trike seat. The other end goes around a piece of 3/4" (inside; about 7/8" outside) PVC pipe. And then I thought, "Hmmm.... if I put a horizontal piece of PVC pipe between the two vertical ones, I could put a short length of foam pipe insulation around it, then put some soft, furry fabric around that, and there's my headrest."
This sort of worked, except it tended to lean forward or back depending on my head position, which made my lights sort of crazy. So I put another horizontal piece of PVC at the bottom of the vertical sections, with four L fittings holding it all together and a drop of superglue at each joint for added rigidity. This all works out because of my seat angle and curve; the lower horizontal pipe rests against the back of the mesh seat and created a perfect angle for my neck to rest against.
Your bike or trike may be different and require two of the clamps instead of the lower horizontal pipe. And -- again, this depends on your trike or bike seat -- you may need (or want) to bend some of your PVC, which you do by filling it with sand to prevent kinks while bending, then heating the sand-filled tube with a blow dryer or other heat-producing tool.
PVC is magical. Cheap, too.
One last note about my light bar: the vertical curved thing sticking up is an 18" Foam Glow Stick held on to the light bar assembly with two lengths of velcro. The sticks cost less than a buck apiece and really make your trike or bike visible at night from all directions, especially if you use two of them.
Plus, of course, you have your regular headlights and taillights, and likely a reflector or two. I like to say, "If they don't see me, they're working at not seeing me." Which, since this is Florida, is entirely possible. Sigh.