Rain Gutter Regatta

My sons Cub Scout pack is getting ready to have their rain gutter regatta. Most of the boys have their balsa wood boats in various stages of completion. After speaking with the pack leader, I found out they didn't have a rain gutter to race their boats in. Since southern California doesn't get much rain, certainly not enough to race boats in the rain gutters, we had a problem.. So I went through several designs of various sizes and settled on this (to the right). It's 8 feet long, and divided by a Plexiglas sheet to create two lanes to race boats in. The tradition is for the boys to blow on the boats (sails) to make them move, so I made the divider tall enough to make sure one boy's boat didn't interfere with the other. The bottom of the rain gutter is a 2x6"x8' long plank that I cut the sides at a 45 degree angle. I then put the two 10" wide sides on with wood glue and screws (I hate nails) every 6" or so. The ends are held in place with wood glue and screws as well. The divider rests in a slot between two slats on the bottom of the rain gutter. The inside of the rain gutter is blue (like water), and the outside is gray (my son picked the colors). At some point I'll add designate one end as the starting area, and the other as the finish line with a painted pattern, and some posts put into the sides. I thought about adding a small bilge pump (batter operated) to create a slight current, but the pack committee wants to stick with tradition.
I chose this design to maximize the width at the surface and depth, while reducing the amount of water (weight). This is also the simplest of the 5 designs I considered (KISS). After sealing the rain gutter, and 3 layers of oil-based water-proof paint (behr representative recommended suggested 2 layers should be enough), it should hold water easily. I'm giving it 48hrs drying time between layers of paint. I'll post actual pictures upon request.