if you're sure of the thickness of your roof those anchors will work. one problem with them, from experience, is if the little tabs at the "head" don't dig in solidly, the whole thing will spin. It will not get tight and will have to be drilled out. PITA.
I used these here: http://www.fastenermart.com/html/060420000120.html
they can be used on any thickness material if your bolts are long enough. I did a pull out test on 3/8 particle board. I broke the panel and the anchor never deformed. buy them at a big box. One problem that is easy to overcome, they need a hole depth of almost the length of the metal anchor part. If the hole is slightly elongated, the depth only needs to be about 1/2 of the length of the metal part. I am impress how strong they are and they come in larger sizes.