Be aware that the expanding foam used to glue the structural foam blocks in place in a Sunfish sometimes expands against the inside of the transom (I have a boat with the stern completely filled with expanding foam). You can carve or punch out a channel through the foam for a transom drain, but water in the hull may not exit easily or completely through a transom drain. If foam-free I like a transom drain, but you don't really know what's inside the stern unless you go to the trouble to install a rear inspection port. The deck drain is almost as problematic. Because of its position it's difficult to completely drain the boat even after rolling it up on edge. Your bow inspection port may be good enough (if it's free of surrounding foam). Lift the stern and open the inspection port. Sponge out if not much water, flip over and drain if the boat's a leaker.