I like to finish the inside of the trays before cutting the dovetails, a sharp plane is best on these smaller pieces, sandpaper tends to round the edges no matter how carefull you are. Also the plane is quicker and with a slightly curved edge I can go straight to the shellac and wax finish.
The sides of the trays are 7.5 mm thick by 30 mm high and I like to get nice clean edges which is not really possible with the planer, especially on the curly grain. My method is to clean up one edge on the shooting board and then carefully size on the table saw. I then clean the other edge up with identical strokes (5) to keep the boards all exactly the same height.
My wooden jointer is both effortless and comfortable to use.