Funny, I remember windowed ceramic parts as being quite a bit more expensive than epoxy plastic with no window, which would be a OTP (one time programmable) EPROM. Use the high dollar windowed devices during development or for unstable projects, then switch to plastic OTP once the code settles down for better production margins.
The good stickers we used were metallized polyster, I think. They were a bit more opaque than paper, as measured by the time it took to UV erase a device.
I'm sure things have changed, but the last time I made stuff with EPROMs was back in the 80s. When cleaning out a garage back in the late 90s, I threw out several old arcade video games (She Who Must Be Obeyed had commanded it), and the stickers had fallen off all the EPROMs.
The good stickers we used were metallized polyster, I think. They were a bit more opaque than paper, as measured by the time it took to UV erase a device.