Apart from using a bungee to get a very fast speed BEFORE you open the throttle there is a CHEAT but you NEED TO BE CAREFUL.
I tried to over power my first FT Spitfire a long time ago now and it did not have any landing gear so I had to give it a rather hefty throw. Even at half throttle it would turn and then roll/dive to the left on launch. I knew that it was due to "P" factor so in desperation I did a mix via a switch to deflect the rudder to turn right on launch.
It reduced the launch problem but I needed to be quick to switch it off as the speed rose or it would turn, roll, and dive to the right!
Eventually I settled for landing gear and as much rudder deflection as I could reasonably obtain. It still would want to turn left on the opening of the throttle and would crash immediately if I took off too soon/slow. So the rudder held it straight as the speed built up and once travelling quite fast on the ground I would let it rise off of the ground at its own pace. Besides it really amazed the locals when it lifted off at full throttle and I had enough pace to then point it skywards and do a vertical zoom climb before resuming normal flight.
A ground run trolley is another option. The trolley has tail wheel steering via its own servo which is connected in parallel with the rudder servo via a "Y" harness. The Trolley socket on the "Y" harness is fixed to the underside of the fuselage, (facing rearwards) and the plug on the servo in the trolley is sanded slightly so that the slightest pull on the servo lead disconnects it from the "Y" harness.
Just a few thoughts!
Have fun!