Development note:
To get an approximate double tapering of a beam for resisting buckling while aiming for least mass while aiming still for some nestable parts for packing:
During assembly, semicircular reinforcement plates are applied to the central region of the kingpost and queenposts (or downtubes). These plates, shaped to match the curvature of the masts, are then secured using reinforcement bands (Velcro straps) that snugly wrap around the masts, increasing the overall resistance to buckling in a lightweight and efficient manner.
Another option for the same scene might be the use of three segments for the kingpost, three segments for each of the queenposts. JoeCups might be used for the joins, two per beam. The two outside segments would fit into the central segment; the central segment would be stronger for the resistance to buckling.