It seems like this one is really fun to hunt, I usually hunt him when I'm doing a full time hunting, that means when I'm hunting Goblin Gruel, spook and Crypt Ghost!
I hunted them all today, I ended up with 3 slack. I think I killed him like 9 times today, no one managed to voke it from me (not even a PLD75 in some special armor, not even 3 japanese mages that was in PT^^)
The bats(there is 3 bats in the room. there are only 2 bats if Crypt Ghost is there) in the room spawns like 3 hours (van'diel time) after they are killed.
Crypt Ghost spawns about every hour(real time). For example: If you came there the day before and he was allready spawned, you killed him at 07:00. Then the next day the bats spawns at 06:00, he will not apear then. You kill the bats, and wait for 3 more hours. At 09:00 does the 1st bat apear, now Crypt Ghost will replace 1 of the bats.
Before I had TH2 i didn't get any drop at all, I had killed him several time... but still no drop. It seems like TH2 really helped out on this one!
If you choose to camp this one, you might as well farm bats wings! It may sound stupid, but If you hunt it for like 10 hours one day (like I did today, I didn't have any work today!^^), then you might end up with alot of bats wings in the end. I also farm "Cotton Cloth", spook and crypt ghost drops it. If you are a THF, then you can steal it from them...
Good luck hunting it, ask if you have any questions about this one, because I've hunted him for ages! I know him too well^^
btw... I earned almost 200k in king ransperre's tomb!