Mo, the best answer is … do the math. It looks like you are on the right track. Start with a sketch of the geometry like you have on the plywood in the background, then scale the lengths in terms of trig functions of the angles. Make models out of bristol board and wood (like in your photos).
You need not do the trig - every angle in a Hip/Valley roof may be developed with nothing more than a compass and straightedge. I prefer to make a worksheet or program to solve all the angles:
Hip and Valley Roof Framing and Joinery Angle Calculators ... print the list, and final dimensioning is done in the field with a scientific calculator (the programmable graphing type preferred). If you understand how to derive a formula from the geometry then by default you will know how to apply the trigomometry to dimensioning the roof components.
I only have a few minutes of time online today so for now here are links to a couple of roof framing math discussions:
Roof MathHip and Valley Roof Compound Angle Formulas and GeometryOnce you get the hang of it there isn't much to "complex" roof joinery. It's just a bunch of right triangles. See you all next year!
