Not sure this will help, but I have about 500 P2 hours in my logbook.
Military Gazelle (Single engine, and also very definitely a single-pilot machine). Subsequently about 1000 P1 hours (and when flying with a co-pilot, he was logging P2). No instructors in sight.
No question that I shouldn't have logged those P2 hours, so...? Something different for the military?
Safe flights, Sam.