It seems to work OK for me. Try the attached file which is a camera figure smart-parented to V4's rHand. You will need to loose the ".TXT" part of the file extension.

Here is what I did. I loaded V4, turned off IK, zeroed the figure. Loaded the camera figure positioned it in V4's rHand, mostly by moving and rotating the BODY. Memorized the camera figure. Set the Figure Parent of the camera to the rHand. That parented the BODY actor, which is the only one you should normally parent to another figure. Saved the camera as a single figure.

Lastly I opened the Smart-Camera.cr2 in a text editor, and in the BODY actor, changed the line "parent rHand:1" to "smartparent rHand".

Like is said, it seems to work OK, with the camera assuming the correct position relative to the hand. Note that there is a known problem wit smart parenting figures, if you try to delete either figure, without first unparenting the child figure, it can cause Poser to crash or hang. My Smart-Camera figure makes use of the default Poser "camera.obj", so if you have multiple runtime folders, it is probably best if it is install it in the same runtime as the default Poser content.