Sorry mate but I cannot see how a disclosure form would help in that situation.
Just because we have to reach across someone from time to time, that is totally in line with normal aviation practice. I don't think that there would be any sort of case to answer, because it is how you are supposed to operate the machine. I'm PIC, therefore it is my responsibility to ensure that the flight is conducted as prescribed in the POH.
At the end of the day, as an a/c captain, you are entitled to do what you need to do to make sure the a/c is safe. If that means throwing a passenger out of a window or reaching across and brushing someones leg, then so be it. As long as it is a necessary action.