Just my thought on the subject, but if they are continuous duty pumps, using the bypass filter and return line to the tank shouldn't really affect your fuel pressure.
It does depend on what the original flow and pressure the bypass filter is designed to be used for, as the return to tank line should have a metering restriction to only allow over pressure/flow to go back to the tank at the designed rates.
Theory testing needed to determine the filter output to carb pressure, which I gather is your plan.
I look forward to seeing your results.
