Fuel Filter And Fuel Pressure.

I note the latest fuel system recommendations from Rotax include a check valve between the pump and the outlet of the high pressure filter with a minimum opening pressure of about 11 psa (0.8 bar). My understanding is that this would allow fuel (albeit unfiltered) to bypass a clogged fuel filter and keep the engine running.

Now, like the Rotax diagram, I have a pressure gauge before the filter so  that would read the standard rail pressure (assuming the pressure regulator is working correctly) plus the pressure drop across the filter.

So what would that gauge read just before that check valve opened? The answer has to be close to 11 psi plus 46.4 psi, say 57.4 psi. If it gets that high, you definitely have a clogged filter according to rotax.

So what SHOULD be an upper limit for that indicated fuel pressure? Should I just assume that there is no pressure drop and set the upper limit at 46.4? That I think would see me changing a lot of filters (at $90 each!) or should I make an allowance for the pressure drop of a partially loaded filter say 5 psi, that would mean changing filters before 100 hours if the pressure went over 50.4 psi?

What are your thoughts? When should the filter be changed?