Crawled under the GV yesterday to check the fuel tank mounting. Confirmed it is 100 gallons. Saw a "sump" looking feature that creates a low point on the tank. It has a drain plug. For draining/checking for condensation water? If so how often should I test drain?
Drained mine once but after getting an armpit full of diesel, decided to use a small 12 volt electric pump with tube attached , tilt the motorhome and drain a small amount of fuel for inspection. i always keep a full tank so I worry about not getting the plug back in a timely fashion or crossthreading the threads and making a mess. I do this from the fill neck.
You probably have a water separator installed that would let you know if there is water. Water sinks to the bottom is pumped out first.