I didn't say that you have to run it with the Dash, i did say that it is not a cheap option.
To start to get some good results things like steering angle, pedal travel or brake pressure and perhaps something like looking at the differences in temps across a particular section - for instance the intercooler, you will need additional sensors.
You will need to do a fair bit of stuffing around to plug the factor sensors directly to the DL1 and measure the voltage differences which is a pain, to be honest when you look at it you get good value out of the performnce box unit that has everything done for you and easy to move into and out of different cars.
Coming back to the rear wing Roy's idea sounds the best option,
Matt