I am dealing with the same issue on a wing with flaps & ailerons on each side.
I have ordered some balancing plugs, male & female, with pigtails from Radical RC.
Each wing needs a +, -, and two signal wires. A 3S balance plug will work.
Then you only need to plug in two wires.
You could also use a 5S and have one plug.

I'll let you know how it turns out.
KW_Counter