Have a default auto transmog on bows if not using an alternate appearance.
Make it available to all races…
but you have to sacrifice a level capped character to do it.
Get to cap. Do a LOOOOOOOOOOOOONG quest chain. [8675309 confirmation buttons] Character loses old class and is now a Tinker at level 10 in a base set of gear.
There’s more than enough out of place class/race combinations in the game for blizzard to struggle fitting into the game in the forseeable future.
That’s literally never gonna happen. They were going to do it with Death Knight, which at least makes sense thematically. If they scrapped it for a class it made sense for, why would they make that a requirement for Tinkers?
I mean, you could just have Mechanical looking bows. Compound bows with gears and springs and the like.
It doesn’t have to be realistic. not in this universe.
This is a horrible idea. 
Please don’t. Blizzard realized that was a bad idea as far back as Wotlk.
I Imagined a Sheepinator 9000.
Rogues can drink healing potions and craft poisons without ever interacting with the Alchemy profession.
Tinkers can use the same logic re: Engineering profession.
Time to add the Tinker class. I’ve wanted a healer with a pet (medibot) ever since WoD nerfed MoP smarthealing into the dirt (and then Legion stabbed Atonement, Dream of Cenarius and Fistweaving’s corpse a few more times just to be sure).