Ive watched many pt vids, ai and alpha
From what ive seen the best camera placement for laying flat cg rcg, is back just enough to where you see guys upper shoulders in frame and aim the cam straight not angled up and have it low to the guys face.
I know the angle up wards is for upclose face to face and kissing so heads won't get cropped out but in pt an angled up cam causes scale issues the further heads get away from the cam,
The aimed straight approach and low helps parallel male models with the viewer in laying flat cg rcg...and is most realistic looking. You can get by with angles up wards but imo looks kinda off and not realistic. Also depends how low or high the cam is, it needs to be low, if it's to high then it harder to parallel models body to our.
The height position is important in pt, the cam is basically our eyeballs. I think you can have an angle, cuz in laying flat position im pretty sure we using like a pillow under are heads, so a slight angel wouldn't hurt but the cam needs to be low where our eye balls would be. /π.
Ai pt can really show what scale size and camera angles work in vr. π