So, here is my opinion, I think that you don't have an issue
However, I like what you are trying to do. Now the post above is 100% valid, if you are collapsing a hose, that'd do it.
However, 210-215 cruising that recovers quickly is pretty darn good. I would even say that depending on the gauge, sender, and voltage the car is running, that there is a variance there, and you could even be cooler than the gauge shows
Is it an electrical gauge or mechanical? If electrical, would ask one of the engineers what an electric thermocouple does with extra voltage, would the variance show higher on the gauge or lower?
Another thing you could do is gut the thermostat or run a purpose-built restrictor of about the same size. it would take out the "opening temp" of the thermostat out of the equation. However, I would not run without one, as an engine likes some restriction to force water everywhere inside the block and minimize hot spots and cavitation.
However, I can't see a reason to spend more money, if you really wanted to, make some rubber flaps in the shroud for air to go around the fans at speed, but you'd need quite a bit of area to make a difference I think. Maybe not though if in the right place, like the 4 corners