They don't need to be transparent, make them like the animatronics on the ride. They won't have the same look without the screen and lighting, but I think they'll look nice. And I would totally buy them. Right now I'm dying (pun not intended...) to get ahold of the WDCC Hitchhiking Ghosts to go with my Spirited Entertainer (The Organ player) piece.
I'd definately buy them. The easy way to make them would be like the three 1/2 scale statues that Disney released in the parks in 2007. The clothes were white and the bases had blue L.E.D.s that lit them up, pretty eerie looking in the dark. Here's a better pic of the Ezra Dobbins one.
I can't see the first pic, but the second looks pretty accurate to the ride. I agree that is probably the best look for them, but I would personally like something that would look good in the light, even if it sacrifices some of the good look in the dark.