Make it like the Caterpillars if you can. Their upper and lower sieve adjuster is already tied into the Combine Electronic Business Information system. One knob lets you switch between upper chaffer and lower sieve.
Nice idea, but what you also need to check from the cab then is the loss on the ground. The loss monitors from CASE and JD I have seen so far are not accurate enough to stay in the cab. You still have to get outside to check the ground anyway. Only the CAT grain loss monitor was really accurate enough to do so. It is the only one I know of what checks the loss over the whole width of the seive area.