Effects of wind

A couple of things to consider regarding the effect of the wind on your ability to control the boat. The shorter and wider your boat is, the more effect a tail wind will have on your control. Two things are happening here; short water line and more surface area exposed to the wind. The wind is pushing on the above water surface area at the stern and the this causes the a spinning effect with the short water line. Best solution is the trim the stern heavy and paddle harder.
The other part that wasn't mentioned is the amount of time the wind has been blowing and the resulting waves that have been created. Waves compound control problems as they effect the boat below the waterline.
For all the people that suggest that a particular boat does not need a rudder or a skeg, I would recommend they try to paddle against waves at their stern quarter. In this situation, virtually all boats with turn (actually be pivoted) into the waves and will benefit enormously from a skeg and even more so from a rudder.