You might add a few holes to the tray corners to make it easier to clean and/or allow water to escape (with all the fish you'll be catching, you don't want the weights to be off because of water runoff in the tray - or do you?). If you decide to do so, I have found that drilling those types of trays can often crack them. I have taken to heating up a awl or Phillips screwdriver with a light duty propane torch and melting the holes through.
And, you might try to avoid gluing the mat in so that it can be removed for cleaning.
Just a few thoughts.
