I got the final sanding finished on the two blanks this afternoon. I knocked off the spackle high points using 180 screen and did a second pass with 400 screen.
After the sanding, I measured out the center point of where the mast will mount, and lined up the reinforcement blocks. I'll route these holes out in the next day or so and get these glassed in (fiberglass underlayment, epoxy slurry fill, mounted flush to the bottom deck).
I want to get these done, but my massive aversion to glassing is forcing me to find all kinds of reasons not to glass - repotting plants in preparation for an upcoming plant sale, cleaning the garage, picking weeds from the landscaping, running errands - and many more. That said, I believe a purpose built foil board will help shorten the learning curve so that is what is making me take the necessary steps towards getting these boards finished.