My concern about using many short timbers between the rafters is fit and precision. How far would the plate bow outward before all of the sections of the A-B compression beam come into full, load-bearing contact after shrinkage of the rafters? Other than that, as long as the A-B timber is in, or close to, the same plane as the rafters, I don't see why this wouldn't work.
I'm not a PE, just a mech eng and TF ameture.
