OK. I understand the reason. The concept can work. As I see You can do it with cutting the PPM signal between your radio, and the module, and You can insert the Arduino in between. For receiving the radio ppm signal, this library is OK.For regenerating the PPM signal maybe the loop{} can do, but because it is time critical I suggest a timer based solution instead.
I have a PWM2PPM project, which I wrote to create a PPM signal from my old PWM receiver ( PWM signal reading problem - Programming Questions - Arduino Forum )
You can cut the PPM generation part from it, and the loop role is only the data transfer, and the ADC.