1990 Prostar 190 Stereo Cover Replacement

I sat on the the flip-up cover for my stereo and broke it. Can't find a replacement.

It's located right under the mirror on a flat section that only about 2 3/4" high.
All the waterproof radio covers that are for sale are really big.

Does anyone know where to get a replacement cover, or have any suggestions on somewhere else to mount a stereo in a 1990 Prostar 190?

Thanks,