Don't use a glue as a fairing compound, you'll regret it as soon as you have to sand much of it off, which in the case of most fairing is a large percentage. If mixing your own, use a combination of micro balloons and or quartz spheres with a touch of silica to control stiffness so it doesn't sag on vertical surfaces. For most novices I recommend using a premix product such as System Three's "QuikFair". Until you get pretty good at mixing you own, the premix stuff is superior and more importantly consistent. If you already have the glue on, take a grinder to it and knock it down with something mean, like 40 grit or less, and save your elbows (trust me on this). You can go back and fill in where you need to with the smooth and easy to sand premix later.
Your scupper just isn't going to work as well as you'd hope. They actually sell a device that does as you've envisioned, though they're not cheap, they do work well. Look into an "Anderson Bailer" or similar product.
This is one of the cheapest I've seen, but you can find them on EBay cheaper > http://www.duckworksbbs.com/ronstan/ra554130/index.htm
For your boat, you just don't need one frankly. A simple transom drain (with the appropriate plug installed) is the common method to drain the boat when on the trailer. When underway, you'll want to use a bilge pump instead of a bailer. The bailer shown above is typically seen on sailboats and needs a fair bit of speed on to work effectively. A powerboat can easily do this, but not a rowboat. Generally you need to be going several MPH for them to work well.