James, I’m glad to see that you’re using our DIY Mayfly-Modbus-Wing. Yes, soldering the DIY windshield is required. I had thought you were discussing soldering an RS485 adapter directly to the Mayfly. My bad for misunderstanding!
From my perspective, there is not “problem” with the YosemiTech Y511 turbidity brush running every time the sensor wakes up to take a measurement. You might have read of some issues back in 2017, but since we massively improved power management shortly after that (via ModularSensors improvements), we have had no power problems.