I have two different designs.
A) Split with a hinge in front. The top lifts up. The sides are wedges bulged slightly at the front. All convex - no concave.
B) One piece that slides back and tilts forward. The bottom gutter edges would have a couple inch fillet (hard to draw).
Notes:
- Both match cab shape at the front for smooth transition.
- Slopes are all less than 22 degrees from normal.
- Compound curvature using fiberglassed (similar to T's).
Which would you prefer and why?