I installed a 1-way check valve and so far, no issues with startup and low tank. Camping this week and will report back if it is successful.
The check valve was placed from tank to pump before the filter as shown above.
Below is the airdog that was placed by robs 4wheel drive in Clackamas, OR. They did high quality work with the custom bracket required for van application. They placed it inside my rear battery cage. You see it here behind the gas tank and the custom transmission secondary cooler. The airdog is on the chassis in front of my rear underside storage box.