What do you mean by hardwiring? Out of curiosity.
I don't really understand the need for wired-control, but my first thought would be an ethernet cable to later on control the drone through ROS for example. Maybe even using a ground control station software like APM Planner 2 to control it with the joystick, as you might be able to set it up there as an alternate controller.
Are you talking about controlling a copter though? That just sounds extremely dangerous.
I'm still surprised by the "wired" part of your project.