I just realized I left this thread hanging. I ended up trying turmeric in Everclear. It did indeed stain my arrows a nice, bright, but natural-looking yellow. Unfortunately it took me a few days to get around to greasing the arrow shafts. I didn't want to grease the wood before I fletched them (afraid the fletching wouldn't stick to the grease), and being fairly new to using raw turkey feather, it took me several days to get them finished. By then they had faded to a light, yellowish brown. I think I'll try again, maybe dying the already-fletched arrows so I can get some coating on them right away. If oxidation is what caused the fading, that should help. If UV caused the fading, nothing much will help. Stay tuned...
Thomas