I make a living shooting interiors with the K-3. Photographs are produced using a mixture of ambient light and off camera flash. It is difficult to get a proper idea of exposure and shadows cast by the flashes from the camera display. So in lieu of the missing lightroom plugin, I connect a 13.3" display via hdmi port and review the photos on the larger display. Display is powered through USB port, with two battery packs mounted on the stand.
Works very well for me and saves me loads of time on set overshooting to make sure I have all the photos I need. I have plenty of scenarios where the lightroom plugin would be invaluable, but until Pentax catches up this will do.