What are the optimal rear bag rider dimensions (F Class)

What are some common dimensions for the \_/ rear bag rider stocks/chassis used for F Class or BR. I know the width is directly associated with the rear bag flat spot but I am mostly looking for the angle of the sides.

 

I run a 1/2” flat and 20 degree side angles. I use a Edgewood Gater bag. I have tried the long ears and get vertical. The short ears are filled pretty solid but still have some gives that lets them act as a guide. The flat goes all the way to the top of the base bag. I see this design as a “knife edge” guide.
FYI - I hate it but I have to adjust my front rest ( no matter what brand) during a string. I have learned not to force the shot stop and adjust.

 

The angle and flat are selected to match the stock. Bag manufactures have gone so far as to name the bags this way. Some angle variance can be resolved by purchasing a narrow or lessor angle and pounding the rifle into the bag, conforming it to the rifle.