Yes, it is a very crude solution, and I'm aware of it's limitations. I just thought it might be a nice short-term solution (since you mentioned that your time is limited in the other thread).
My take simply is - the lightbox is supposed to help appreciate images larger, and with less distraction.
But that very purpose is often reversed on small screens (for example: http://www.alex-kunz.com/portfolio/black-oak-in-fog/ - opening this in the lightbox on a small screen will render the image much smaller).
So, in order to give the mobile/small screen user an image as large as possible (so that it can be appreciated as good as possible on the tiny device), a simple solution would be to simply open the image "full-screen", as is, without a lightbox at all.
As for the more refined approach, I could imagine an "invisible" lightbox that displays the image full-screen, with gallery navigation and title/caption fading out after an initial delay, and coming back in when the user taps the screen. Something like that.
I think the lightbox-type plugin where I saw this option first was for Slimbox, or Slimbox2, I can't really remember.
Thanks for being such a great and responsive developer!