I don't know how to quantify what is enough and what may be too much of a reaction, but it is clear that you are successfully producing significant reactions using the anal sphincter contraction. In any event, in the context of a polygraph examination, your reactions while answering the "control" questions will be measured against any reactions while answering the relevant questions.

I have no information regarding which departments in So. Cal. are using sensor pads or strain guages in an attempt to detect/deter countermeasures. You'll find illustrations and discussion of such devices in the message thread, Counter-countermeasure techniques.

As an alternative, you might wish to test your ability to produce reactions using mental countermeasures.