Final results for this variation...
Recipe Vapability: 9 out of 10
Recipe Accuracy: 8 out of 10
After doing a little research, I found that FW Ecto Cooler is about the closest flavor to Sunny Delight on the market. So this version adds 5% of it to try to emulate the "heavier, artifical, orange mouthfeel" that my previous recipe was missing. I suspect this attempt will be much closer to the actual taste of an Orange Crush.
This was the best yet. It's still NOT QUITE all the way there, but it's close enough, as I think I'm done chasing this flavor profile. It's still missing that heavy mouthfeel, but the taste is pretty spot on. I'm thinking possibly adding a hint of marshmallow to thicken it up might do the trick. Possibly a little bit of Ethyl Maltol. That's the direction I'd go in to perfect this.