Quote - well the easiest method if you must do this is to export the conformed posed item, reimport welded and then drape that

That would indeed be the way to proceed. The conformed mesh would of course have some un-natural stretch but that may be acceptable. 

The process could be automated in an add-n, somewhat like Snarly's SubD add-on. The script generates the object mesh copy, hides the conformer, and sets up the cloth drape. If the lothing has complex shaders those would have to be transferred too. 

A second phase of the add-on would be the deletion of the simulation, removal of the object, and un-hiding the conformer.