I am not in favor of ever drilling into the middle sections of the roof.
At least you have wood under yours - My roof is fiberglass on the top that has a slight slope from front to back - then a small layer of filler foam on the inside that varies from two to three inches deep - then the 1/4-inch ceiling wood... It does have very small width wood trusses across the roof under the fiberglass
My plan is to use long ALUMINUM UNISTRUT pieces all across the roof and tie into the stronger end side sections of the roof which is 3/4-inch wood side sections.
The panels will be attached to the unistrut spring nuts that can move anywhere along the inside of the unistrut frame.
Even just using standard aluminum angle material all across the roof would work well using this method...
All PHOTOS from GOOGLE Images
In my case there is no way I could successfully drill in the middle sections of the fiberglass roof and try to hit the very small width roof trusses...
Roy Ken
