All my darkroom surfaces are finished with several coats of marine spar varnish (first coat cut in half with thinner to help penetration). At 20+ years old, they still look like they did when new, except developer will stain if left to dry, but the surface is still good.
I second the fiberglass screens. I had some like this years ago (I hang my prints now), wooden frames. I just stacked them, but this will allow more air circulation. (I didn't finish the frames, never a problem.) You need to be able to clean the fiberglass with a weak clorox solution from time to time to eliminate contamination.