Adding a second tank sensor display near the tank valves

No need to fill the tank. The solids are on the bottom. I run my flusher while watching what comes out through a clear fitting at the start of the hose. I may close the valve briefly during the process but only for a minute or so. Been doing it this way for many, many years. Never a problem. As far as the gauges go, I never pay any attention to them as they never work.
B.O.