Let's go back to elementary school and trace out the 1/4" lines with the Sharpie. This will solve the problems with the difficulty of being able to see your exact measurement.
Now that the visibility issue is solved, let's make this thing float. When you turn the board over you will see a channel running lengthwise on each side of the board.
Lowes and Home Depot sells "Great Stuff" for under $4.00 a can. You will find it in your construction materials section. Take your can of "Great Stuff", shake it up, and run a bead of spray foam all the way down the length of the channel. Follow the instructions on the back of the can. This will take a few hours to set up and cure. Don't worry if you didn't fill the entire gap with foam, this foam expands as it sets up. Once the foam has raised like a loaf of bread and is dry to the touch, run your razor blade down the board to cut off the excess foam. Presto, a floating Hawg Trough!
Now that you can see all your measurement lines and added some foam, you can throw on your sticker of choice to add a little personalization.
With a couple of simple mods, this handy tool becomes even better! If nothing else, it gives you a reason to play with your fishing gear when you're not on the water. Now go get on em!
~See ya on the water!