Holy crap, that roof cut is SCARY.
I'm with Patman, I would have thought they would have a template.
I have to admit, though, that I'm not intimately familiar with the penthouse construction - Are those fasteners holding the "tent" to the body, or the top "hinge" mechanism, or what?
If it's just the tent, it's probably "acceptable" in that the tent shouldn't be pulling up on the roof too much, but if that's "structural" in the sense that the weight of the fiberglass top, mechanism, and anything lashed to the roof is depending on those fasteners.... well then I'd be looking into having someone make me a backing plate to "sandwich" the roof sheet metal.
EDIT: Looking at the other pictures I'm a bit confused. I see a line of self tappers outboard and parallel to the cut, so I'm guessing THAT is where the tent material attaches (the GTRV pop-top I transplanted was done sort of like that, so I copied it). My GTRV included a "ring" of welded steel plate and c-channel that got riveted to the roof for the entire perimeter of the roof cut. When I did the transplant, I rough-cut the roof a few inches "small", riveted the ring into place, then used the ring itself as a guide and ran the nibbler around the ring to trim the roof straight and tight up against the ring. I guess what I'm saying is that I'm surprised there's no reinforcement there, and more importantly I can't really figure out what those fasteners DO. I guess they attach the shelf/trim thing that's up in the bunk area I see overhanging the roof?