Back during the Civil War when I started fly fishing, the Confederate soldiers used to tell me that a Muddler Minnow fished dry was a great hopper pattern. They were right...
For that reason my hoppers look a lot like Muddler Minnows and have a deer hair wing. IF I want to get scientific, I may slap on slips from a turkey wing or tail...
In the natural brown color...
That being said, I'll go on record as saying terrestrials have different colorization depending where you encounter them, BUT they are opportunistic meals so when they land (with a splat) on the water, 99% of fish will clobber them regardless of size or color.
That's the reason I tie only one size ant, beetle, bee, inchworm, caterpillar, cricket, hopper or cicada...
If it HAS to be olive turkey; feathers aren't the hardest thing to dye. I used to custom dye a ton of materials, not because I was convinced exact shades mattered, but because it added a fun element to my tying.
Good luck!!