Oh god. This is the stuff of absolute nightmares. Your persistance (insanity) is admirable, however!

I'd imagine wing veins as a series of half cylinders that droop outwork, then back up, with a thin "membrane" of polys that then link together. The alternative is to try and achieve the depth and detail through a normal / bump map later, so long as you've got enough detail in the mesh to allow convincing deformity if you're going to animate.

Keep at it!