Ok, I see some conflicting interests here. On one hand you strip the Cessna of everything to save on mass, yet now you want to install some of the almost-original functionality back into it hoping to impress the audience. Do you want to win the race or just have fun?
Screw the arduino, motors, MOSFETs and transistors. Install a cable and pull the flaps by hand so you can wave at the audience while tipping over in a tight corner.
If you really want arduino, put some LEDs on the plane. Heck, put a whole bunch of them and set them up for an epilepsy inducing choreography. Audience is cheap and will be impress a lot more with shiny LEDs than flaps on an airplane.
Are you using the Cessna engine to power that thing?