Yes you are correct double sided or capped clothing will not work because some of the mesh will be in contact with the figure when at the zero pose. Try this, it may not work with every item of clothing but it will give you a start.

• Load the clothing figure into the scene.
• Turn IK chains off, zero pose and zero body and hip translations.
• Select a body part. Use the grouping tool to assign all the unwanted faces to a new group.
• Invert your selection, and spawn a prop.
• Repeat for all other body parts
• Delete the original figure
• Export the spawned props as a single OBJ. If you are going to use this as dynamic clothing then your grouping is not important. I exported with "Include existing groups in polygon groups" and "weld" selected.

You may have to weld the groups together if exporting does not catch them all. To do this use the weld tool in UVMapper. You could also assign it all to a single group. Save and import it back into Poser and use the Weld Group button in the grouping tool pallet.

Hope this helps.