I'm no expert on P factor either but there are a ton of pattern airplanes out there that have what is called a Canilizer. This is a small wing placed just behind the canopy. What is supposed to happen is the airflow that leaves the prop is doing so in a corkscrew pattern. The canilizer straitens the airflow before it gets to the tail section thus eliminating it's ill effects. I have not flown an airplane with one of these devices so I can't say how well they work if at all. I would like to assume that because so many of them are in use that they do work but pattern being such a trendy nitch I'm not so sure. The fact that most current pattern airplanes are running electric setups with prop sizes in the 20X14 to 21X14 range, the P factor is most likely more pronounced. My pattern airplane has a current electric power setup but being that I like more scale appearing model does not use such a devise. At this point, it's not any lack of performance that keeps me from scoring better, it's lack of practice. Note the pictures, one shows the canilizer. The other is quite funny, it shows a canilizer on an airplane that sports a contra rotating prop setup. Theoretically, that setup is supposed to eliminate the P factor and any side torque.

For the OP. P factor is really not a factor on the airplane and engine setup you are flying. The prop is just not going to generate enough to make a difference. What I think is happening is that you are seeing the effects of torque. How much right thrust do you have? A combination of the proper amount of right thrust and rolling on the throttle gradually on take off should eliminate most need for right rudder. The other thing to check is to measure to see if the airplane is built strait to begin with.