Seriously good advice from previous posters. I'll add my 'horsey person' two cents (for what it's worth). If you have a (not judging!) middle-aged, East Coast female wanting to purchase custom driving harness (in whole or parts) I can almost promise you she has seen every scrap of harness from here to England and liked yours the best.
You know how horse people are with tack. If they love it enough, they'll pay for it. Last set of harness I worked with was oil-dyed, Amish made mule harness (large, draft size). Weighed a ton and you could not tear it up (trust me, the mules tried).