The Yakima Wide Body Bracket does not come with a doubler plate but with four bolts and four washers with nuts. I may look for a doubler or fabricate one of my own to make sure it is beefy enough, though there are no complaints in reviews about cracking of toppers from using their washer system. . . .
https://www.etrailer.com/Accessories-and-Parts/Yakima/Y08001.html
Another question.... having not drilled through the Fiberglass "beams" in my cupboards I am not completely sure of what material they are comprised. I assume they are solid fiberglass.
Does anyone know? Has anyone drilled or cut through those "beams".
Thanks. . .
Oh, and thanks for everything you have offered thus far. I must say, this forum is quite cool . . . I can sense the excitement and stoke that everyone shares for their rigs and projects and it makes me smile to read and learn on these pages.
Gratefully,
YoungSage