You might try making two hatch boards - the lower board from acrylic and the upper board from marine plywood (varnich the plywood). That will give you a strong point to attach your companionway lock and some visability and light from inside the cabin when the boards are in. I also made a set of companionway screens (two) for Paloma - I took the measurements to a screen shop and had them made for under $10 each.
s/v Paloma, Bristol 29.9, #141
Slipped in Bahia Marina, easy access to Corpus Christi Bay and the Gulf of Mexico.