I hit the sides with a light coating of white glue. After the glue dried, it was lightly sanded.
White paint was sprayed into the spray can cap and brushed onto the sides of the fin tabs. Again, a little sanding and another coat. This gave me an even coverage of white.
I still had some dips in the fin tab seam.
I applied a little wood filler and sanded.
The reflected light in the picture shows the sanded area around the tab.