People can be dumb like that, but I do understand that crowded camps get annoying. >.> I have to deal with a PLD occasionally Ochain/AE burning all the bats in my spot, and it annoys me, but I just steal some of his mobs; if he's gathering them all up, then he can spare a few. If I had a little more confidence I'd just Sonic Thrust the lot of 'em for killshots... but I'd prolly find myself dead. xD
Anyway, I mentioned it but as it was a little snippet, I'll say it again. If you go to the Woh Gates subzone (by subzone, I refer to the secondary Gates zone that you use a crystal to teleport to rather than walking), and then go to the southwest corner, there is a large room filled with bats that con VT-IT. You'll have to use some acc gear and prolly food (I use pizza myself; long duration, atk/acc), but there's tons of mobs. They don't link, but they do sound aggro, so you have to be careful. Oh, and watch out for the true sight hippogryphs on the way, they're nasty.
As a note, despite the claim that people are so hush-hush with their camps, I found this up on the ffxiah forums. >_> Someone asked for good CP camps for THF, and someone brought up that it was a good piercing camp. So asking on various forums is prolly a good way to go. I know there was one person around here who was like "omg my bat camp" but most people don't seem to get all secretive, from what I've seen.