In fact, I've had the idea floating around my head for a while now for "fully ethical" meat, where you don't even kill the animal, just wait around for it to die of old age. Depending on your views on euthanasia, maybe if the animal gets like cancer or something and is evidently suffering, gently kill it to put it out of its misery because that might overall reduce suffering.
Also, pardon my asking a possibly stupid question out of ignorant curiosity, but if you're vegan for ethical reasons, why not eat eggs? My stepmom had some chickens a while ago, they lived lives that seemed pretty happy, they hung around the backyard eating stuff on the ground + the food we gave them, relatively free to move around (we did put up a small fence to keep them away from the dogs and cats, who did not exactly have a stellar track record of veganism, but they were free to roam inside that safe space) they laid eggs, because there was no rooster around to fertilize the eggs the eggs weren't going to go anywhere... did us eating those eggs hurt anyone?