wasnt there a picture posted last year or the year before where someone had taken all the different colored pails and made like a wall of them on their porch and they were lit? Cannot remember if there were any black ones
You can find out for sure for $2 at your local dollar stores. I suspect that the tealight isn't going to cut it if the black is colored plastic rather than painted on. Just do a surface scratch test on a spot that won't face the public. When the plastic is black, the orange is normally more heavily pigmented and the light won't shine through. If the black scratches off to expose orange underneath, then a tealight should work to some extent.
If you find you have to cut out the facial features to allow light through, I suggest orange gift or craft tissue paper rather than fabric. The light will penetrate paper a lot better than fabric.