The location of the fuel pump and fuel bowls on the first Gen PSDs really is not ideal from a service standpoint.
Do some Googling, you will find that the OBS Powerstroke fuel bowls are notorious for leaking. I had a stubborn fuel leak where everything was dry while idling, but as soon as a test drive, the bottom of the bowl was wet. One of the sensors leaked through the body and out the electrical plug, but only at speed. My suggestion is to plug everything you don’t need, rebuild the fuel drain valve but do not ever touch it again. If you have to change the fuel filter, remove the top carefully and use a Turkey baster to remove a little fuel to swap the filter element.
And while you are in there, delete the fuel heater element in the bowl before it comes loose, grounds and strands you.