Howdy and welcome
The weight capacity for the overhead will always be a matter of static or dynamic loading (big words I don't understand) but basically whether you want to carry a lot of weight up on the platform while folded down driving washboard or just need to settle in for the night.
It is really easy to forget how much weight really goes up there.
In our Grandby shell the factory cushions and the extended platform deck very likely add #100 plus sleeping gear and a flashlight or some books to read....and 2 or 2.5 humans....could easily add up.
What were you planning to load up there ?
David Graves