...............any roofers out there..........

The way we do it is with closures that match the panels. A piece of flashing goes up under the trailer gutter and is bent to match the pitch of the porch roof. The closures are installed about 2 inches from the end of the flashing or to where they can lay on a solid piece of wood and the flashing is screwed down to the high point of the ridges. Personally I like to have my flashing folded back on itself to give it a stiffer ridge.

Below is a sample of the closures but you would need to locate the ones that match your panels. These are call R panel and they are what is most common in my area.