Welcome to living aboard
I have a shade in my vberth hatch
. I simply sewed a square in the shape of the hatch out of nice upholstery fabric
2 layers. I then screwed the leading edge of the fabric
shade to the leading edge of the inside hatch rim ( fiberglass
part). This placed mine about once inch below the hatch frame. I used three screws with Finishing washers. The other end of the fabric shade ( aft part) has a piece of dowel Threaded through the shade that keeps the shade taunt. I mounted two low profile pad eyes to each side of the aft edge of the hatch (again right below my metal hatch frame) to attach the dowel to. I whipped bungee to the dowel and attached small bungee hooks to The other end of the bungee( tiny) , which then hooked to the pad eyes.
When deployed it covers the inside of the hatch and blocks all the sunlight. I can also roll it up to the leading edge and tie it in place and out of the way.
For summer and winter I slide a square of 3M Reflectex between shade and hatch, this keeps the heat out in the summer and the condensation
from forming on the inside of the hatch in the winter ( no more icy drips on my head
at 3 am!).
There is probably a better way to attach the aft edge, heck Velcro could work just as well, I just suggest making a nice gap between shade and hatch for insulating purposes , especially for winter condensation
Hope that all made sense, we also have a full awning to keep the noon day sun off the boat.