For mixture, one of the things you have to keep in mind is that there are situations where you'll want different mixtures that the computer can't know about.  For example, you want to go full rich on take off and landing, but lean out for cruise.  How will the computer know what is appropriate at which time?

I got around it by adding a pot to my throttle control and used it as the throttle position sensor.  The first half of travel controlled the throttle body cable, and the mixture was tuned lean until the throttle was completely open.  The second half of the control lever travel increased the amount of fuel in the mixture, with it topping out at about 12:1.