Slider hatch/ companionway plan

I bought my Pageant as a real project. One of the last projects is making a new slider hatch and companionway entry.

The boat currently has a make shift slider and barn doors. I really like the barn doors and want to keep them. (I live aboard, this makes getting in/out a snap) I'd like to create barn doors with the option for drop boards too. The slider however needs some real work. The fiberglass that the slider should sit on is trashed. I'll need to do some fiberglass work there. There are no metal runners.

Here is a link to my photo page.
http://www.flickr.com/photos/44299992@N00/sets/72157604042741376/

I've got several pics of my hatch and many that I've come across that show ideas I like.

I have a "skylight" forward of my hatch and I'd like to keep that. I was thinking the sliding hatch should slide into that area, thus when the hatch is open, as in you're coming in/out, it would block the light from above. There is an example of this in the photo page, minus the glass. During the rainy season, or when I want privacy, I can make a canvas cover for the glass area.

I'd love to hear any opinions or thoughts on this project. I'm not 100% sure just how to create the slider. Right now the temporary slider just sits there. There is nothing to keep it from falling off it the boat was to roll. Any detailed pictures of how the hatch stays in place would be nice. I'm hoping to get a local broker to let me inspect boats and take photos this weekend.

Thanks for the help, thanks for looking!

Justin