Is a crazy camel that lands on a normal camel's square placed under it, or over it?
The rules state:


  Should a camel unit ends its movement on a space with another camel unit, it jumps on top of that other unit.


And also later (not directly relevant but possibly helpful):


  If a crazy camel lands on a spectator tile, its movement is influenced in the same way, just in the opposite direction to the racing camels.


So the rules set out that the crazy camels move in the opposite direction to the other camels, but otherwise follow the same rules. So if it moves into the same space as another camel, it will go on top.