Never competed, but I did encounter sort of an issue back when I was in the US Navy. I qualified for both pistol and rifle marksman ribbons, shooting both left-handed.
Pistol wasn't an issue. For rifle, we had two instructors who competed in military competitions, and one of them was left-handed. He had a left-hand shooting jacket and knew how to explain things to the left-hand mind, which made things a easier.
Shell ejections? Yeah, that's where the right hand world really shows! We used M1 Garands, .308 cal. and it would eject the shells right across my line of sight, just a few inches from my face. Honestly, it happens so fast you really don't notice. You should be focused on the target.
There are pureists in every discipline, but in sighting a target what matters the most is managing to put a round on the target. Who really cares HOW to aim, so long as you are accurate? Yes, some things help as a general rule and for standardization, how to aim a rifle or operate it correctly, and type sights, but most aren't written in stone.
You can take one eye out and put it in your back pocket, who cares, just hit the target, left or right handed.
Being around 11% of the population, we see a LOT of right-handedness. We get it. And we adapt.
