If you cut a triangle out of a cylinder, the result will have three curved edges.
While you want two straight edges with the straight trapezoids.
Alternatively you could bend the trapezoids, which might be preferable.
The [rule of thumb/first approximation] used on the leading edges is 4% of the gross lateral width. IOW 4" for 8ft.
Longitudinal at the rear??? In any case it would reduce the wake area.
The roll-up rear door makes it livable, doesn't it.