It appears to me that OP's question isn't actually about backlit prints at all-- they're looking for something fujiflex equivalent (which is what Peter Lik used for a long time, although I think he's doing at least some work on inkjet now).
There are a couple of film materials that have that slightly metallic fujiflex look-- one is a lexjet self-adhesive, and another is called "Premium White Film" made by DotWorks-- Ilford (i think) used to make one as well, but i'm not sure that they still do.
The one big problem is that with pigment inks, that paper shine doesn't really come through. In order for it to really look like fujiflex with that hyper-glossy feel, you'd have to use dye-based inks, since the particles are small enough to not cover over the surface texture. But then you're into longevity issues with dyes....