We don't need animals to consume plants we can't, because plant food is soooo goddamn more efficient on every metric. We can drastically reduce land, water and energy usage AND still feed way more people with plant foods. We simply do not need to eat animals.
Any form of "sustainable" animal farming I've read up on end up being still less resource efficient than plant foods, AND obviously massively reduced output. So we're truly talking about vegan vs. an ounce of meat a week. That's not a difference worth defending, considering the other obvious ethical issues.
Finally, why do you feel that it's important to argue for "99%" veganism? Do you genuinely believe people don't understand that less is better, but none is best? Do you apply the same argument to other ethical issues, like feminism? Being 99% feminist is a big improvement, but constantly arguing for it in favor of feminism (aka 100%) would obviously look ridiculous. Finally, don't you realize the humongous difference between "we should abuse animals for our pleasure less" vs. "we shouldn't do that"? A whole class of racism disappears if we get rid of the association between "animal" and "lesser moral consideration".
But that isn't true anymore, right? Renewables are now way cheaper per produced Watt. And still, we're stuck with people pretending that's not true.