I am going to use some of the light weight aluminum UNISTRUT pieces.
I will run the UNISTRUT across the trailer and mount into the roof side. I did not want to drill holes in my roof. This continuous unistrut section slot will allow me to slide the panels along the unistrut as I need to to...

This is a close up of the aluminum UNISTRUT section

My install is going to on the roof of my OFF-ROAD POPUP trailer where the added weight of the panels may require me to mount the panels after I raise the roof and lock them in place.
This may be a big over kill for what you are wanting to do...
Roy Ken