Adding a humidity sensor to an an old tumble dryer. Possible/desirable?

[Tim Downie]

I've an old dryer that pre-dates fancy gadgets like reversing or "sensor" drying.

I'm guessing there's not much I can do economically about the reversing but would it be possible (or desirable) to fit what I guess is a simple humdistat to it to provide "Sensor" drying?

Tim