It's easy enough with a true backlit profile. The problem is that true backlit profiles need to be made with a transmissive spectrophotometer -- so that the reading light shines through the image as if it was backlit, as opposed to reflecting off of it, as if it was frontlit -- and there aren't a lot of those out there, much less people that know how to use them.
Short of using an actual backlit profile, your second option would probably be to double strike.
However, what you also might find is that once you get a suitable density for backlit, your client may not like the way the image looks frontlit. I've actually done some averaged profiles over the years to solve that problem, but it can be sort of a tricky thing to get right.
But just as with everything else you print, it's the profile you use that will determine the result you get.
(Edited to add: If your application will allow you to do any form of color/white/color sandwich as described by the two guys above, that will achieve your best day/night result.)