Use a local sheet metal company to produce 10' lengths from sheets of 20g galvanized sheet metal...with little-to-no waste.
The dimensions are 9" x 6" with a 1" return on the 6" side.
This provides an L shaped finished product.
2 pieces make up a 10" trough...
Lay the L on the long dimension and screw it down to the roof.
Insulate with your choice of product (Owens Corning Formular Poly-Iso, for example)
Run the plumbing and drill your penetrations.
Once installed, the second L is placed over the top and side, creating a rectangular trough
This design provides "swing room" for wrenches, pliers, etc.
And, only one part number for the fabricator...with only 2 brake bends per piece.