There's a "body" for each of the conformed clothes. I the Poserverse conformed clothes are still a separate figure. Game assets don't work that way. Combining all the clothes with the figure and creating new joint parameters for all the newly created, combined geometry is not a simple task. The "Combine Figures" feature in Poser 11 did go away because it made more of a mess that anything useful. As an example the "Remove hidden polys" that it used would remove most of the eyeballs, teeth and even the eyebrows.. It sounded like a good idea but it just never worked.

What it was supposed to do is the following steps.

One possible work flow would be to load all the geometries in one scene. (V4, Hair, Top, Pants) then re-export them as a single OBJ. Make sure the "preserve existing materials" and "Existing groups" options are checked.

Import the combined OBJ into Poser and use the setup room to transfer a V4 rig onto the combined geometry.

You'll probably get the best result by exiting the Setup room and loading a V4 and then re-copying the Rig and Morphs. The tessellated copy mechanic doesn't work in the setup room.

Now save that figure, let Poser make a new OBJ

Reload and export that with FBX. You should get 1 "Body" and more of a game like figure.

Note: I've done this before but it's been I while I hope I remembered all the steps.