II have Poser 9 (so I can't use GOZ) but here is what I do.  first export the default character that you are using (check what you want exported) as a welded .obj

Then export the dress as an .obj

Import the figure .obj as a subtool, duplicate it, import the dress as an .obj.

Clean the character form of polygroups etc and the same for the dress

form fit the dress to the figure, check the dress mesh export the dress .obj with a mesh density of around 14000 polys.

See if that works for you//  Jan

PS you duplicate the figure because when you import the dress .obj, the dress will replace it