With the left over glue i covered the screw holes. These slots are now 1" (25mm) thick. Plenty of depth to safely screw the stringers in place.
The transom is made from spruce, a light color. Too light. So I plan to stain the wood a nice mahogany color. So I grabbed a couple of scraps of transom leftovers and experimented. The one on the left is untreated with the stain left to soak for a time. the one on the right has a wood conditioner and then the stain was applied then wiped off moments later.
The one on the left appeals more to me. But I haven't made up my mind on it. So i'll let it sit a while and maybe do a few more small tests.