Scared Silly

OK, so I have had the pod for about 6 months and am beginning to do some mods. I have the 2015 178. I want to put a shelf in from the bathroom wall over to the curved part of the ceiling, so it essentially will be only as long as the bed is wide. I will use the window valence to support the back of the shelf. I have taken down the coat rack hanger thing and attached the brace for the shelf on the bathroom side wall. I went in through the plumbing access and put blocks in that space to screw the brace into so I wasn't relying on the luan to hold that side of the shelf. Here is the part where I am scared silly. I need to attach the other side of my shelf somehow to the curved part of the ceiling. Does anyone have a suggestion as to the best way to do this? I have watched the factory tour online and it looks as if there is space between the ceiling and the outer shell of the roof. Could I attach with something like a toggle bolt? Sorry for long post, but I know someone out there has done this.

Thanks, as always!

So there is enough space between the inner ceiling and outer roof to not drill through the roof? From the factory tour video, it looked like there may have been some horizontal studs in there so that would allow for a little space between the two, but again, like I said, scared silly......

Outbound used 3/4" molly bolts.  Here are posts from him, and me.

http://www.rpod-owners.com/forum_posts.asp?TID=842&PN=3

http://rpod-owners.com/forum_posts.asp?TID=1829

I noticed that when I tried the link, I've IMed him to see if he still has the pics somewhere.  His post was from 5 years ago, hard to believe.