Gauge For Propane Tanks

I've tried multiple "gauges" for my at home propane BBQ cylinders and never found anything that was very accurate or long lasting. I understand the most accurate way to know is per a hand-held luggage scale via weight but that requires removing the large RV cylinder which would be a pain.

I find it simpler to just have one tank open and cycle filling the tanks based upon running one out at a time. I usually start the season with two full tanks. The last one used has the manifold lever pointing towards it.