Gaff Boom Stiffeners

[Wrinklybear]

I am shaping a long gaff boom spar and the plan calls for additional side bar stiffeners. However, only the outside dimensions of these are noted and I need to save some weight.

Does anyone have any theories about how much contact is needed between the sidebar and the boom to ensure stiffness? Do I need to cut holes for tackle cordage only, or can I expand the cut away parts next to the boom leaving only occasional contact w the boom itself?