If you only want to have a material on one side of a face you can use material nodes, a material for one side, a transparent material for the other side and a geometry node to set which material is on which side of the face
See attached blend file for example.
I got it to work somewhat. I see it working in the node editor, but it’s not reflected in the 3D window, and after I made a few tweaks, it renders without any textures at all.
Ultimately, I’m looking to make a box, with one side glass, so you can see through to an image on the back face.