The fabric is Sunbrella "Odyssey Brown." I could only purchase it online, which meant I could not be sure it would match the brown in my 1984 original "Earth Tone" mainsail. It came out pretty good - same basic hue of brown but a little lighter than the brown in the sail.
I thought about adding a mesh pouch to it to serve as a rope bag for halyards, but realized (a)that's another complexity and (b)I can just undo a snap on the top and drop the excess halyard into the cuddy.
I used marine silicone caulk on all the screws into the bulkhead.