I found a surplus/discontinued cast aluminum Bomar hatch and installed it in the coach roof over the head. Much better lighting and ventilation.
I removed about 1.5" of the balsa core all the way around the opening and poured in thickened epoxy (fiberglass powder thickener) to reinforce the opening, seal the core, and provide a dense medium to tap for the machine screws that hold the hatch to the desk. Also built a deflection dam around 3 sides to keep water and lines out of the hatch gap. Deck core is 3/4" end grain balsa.
http://bodylens.com/Gallery/thumbnails.php?album=47
should look great, like the stainless surround
you are going to have to replace your non skid though. Any ideas what with?