The first time time I try it, I did exactly like you described & it was a disaster, no bones, no xml, nothing & it crash my game. Only reason I thought the helmet thing existed was in order to limit the HDT to specific NPCs rather than hogging up resources by trying to run havok on every NPC. What about HDT hair can't be exported? This is news to me. This is so that after editing an NPC you can use Ctrl+F4 to export the face gen data files in order to avoid the grey face bug. Since you will be editing actor records, you need to first save your plugin before you make any changes. You can use Wrye Bash to 'emify' and 'espify' by right clicking on the hair mod's plugin and choosing one or the other. Whenever you are finished working on the mod or wish to test changes in the game, you'll need to 'espify' the hair mod (unless it was an ESM to begin with) otherwise it won't behave as intended.
So all you'd need to do is load the hair mod in the Creation Kit as a master and assign the desired hairs to the desired NPCs. The hairs in KS Hairdos - HDT Physics are already set up to work with HDT PE even if used by an NPC. If it is not already an ESM you will need to temporarily 'esmify' the ESP while you do your work in the Creation Kit. All you need to do is make the hair mod a master for your plugin. Hairs that are available to the player are available for NPCs to use.
