I have now looked through the POH for the PA28, C172 and C152, and none say anything about where the PIC should sit. As far as I can see none even state that the PIC needs to be on the left hand seat when solo, so a solo flight from the RHS could be acceptable.
The ANO also doesn't state anything about seating position or manipulating the controls when it defines pilot in command.
Can anyone point me to any reference in the POH of a typical american spam can that the PIC should be on the left?