Fernando,
Yes you can make the On/Off switch controlled by a radio.
An easier (cheaper and lighter) solution would be to use a timer with a delayed start like the Z-Tron or JMP.
I have heard this question several times, but I would never do it myself. I am to afraid of something going wrong with nobody holding the plane. I always picture the wheel snagging something and turning the plane in at you, or the torque of the motor startup yawing the plane in. A stooge is so simple it is cheap insurance.
On the other hand Linheart Smith flys with no stooge and a delayed start. It works for him, but I wouldn't risk it. Maybe he will add his input.