As someone who has had a bit of experience with trying to create a CA race, I'd urge you to make this ET only to start out and see how it takes off from there. If enough people are interested in the race and the lore, than lobby to make it CA. Trust me, I know what it's like to really want to add a new cool race to the server, but in the end I swallowed my pride and agreed to make them ET. Hell, I don't even think there's been any events revolving around the stupid ass ratmen I tried to create. Guess it was for the best, though, doesn't look like anyone would've played them anyways.
I dunno if this is helpful or not, just wanted to provide a perspective of someone who wanted to do something very similar to you.