There are three options here depending on the severity of your disability.
1) Use a steering ball with your left arm and work the signal and wipers with your right arm with the aid of two levers.
2) Use an steering ball and secondary control keypad with your left arm. This has several functions on it, which allows you to work the signal,
wipers and other things on the car.
3) Use a steering ball with your left arm and work the signal wipers and other equipment with another part of your body
using a bleeper switch. The bleeper switch can be operated any part of any limb or your head.