Do a search. Someone eles asked the exact question before.
Also read the Poh. It clearly states that the airflow will hold the window open and is certified up to 100kts or so. It is also known that if you remove the strut, the window opens fully flat with the underside of the wing allowng photographer to hang out more.
Doorless is fine in a C172, I've flown a 172 jump plane with 1 door off. Bit noisey though. Plus you might need a 'chute, plus if it a club plane then no chance me thinks.
Oh and I wouldn't do anything silly with the rudder if I were you, its only a window. No need to fly sideways.