Yes, you can place the main camera anywhere you like. Assuming that the center of the tent is at the at the universe origin, try this. Select the Main Camera, zero all the "Dolly" and "Orbit" dials. Now set "xOrbit" to "-90", this turns the camera to look directly at the ground (if you don't want the camera looking directly down use a smaller number). Now use the "zDolly" dial to raise the camera to the desired hight within the tent. If you are asking how to determin the correct hight for the camera in Poser 4, then I'm afraid I don't know the answer, trial and error is the only thing I can sugest.