History Evaporusting the holy part of my tank

Is there an easy way to block off the sender unit hole on my gas tank so I can flip her over and soak the other side

 

How does the sender attach? Make a "blank" and attach it using the gasket?????
Hard to answer with no pic or info....

 

Try any old piece of tin, maybe an old can ( gal? ).
Use a nail on wood to punch matching screw holes.
Then an old inner tube to act as a gasket.
Arts and Crafts

 

Cut out a plug the same size as the sending unit and put it in with the appropriate "O" ring or gasket. On the ones with a locating slot, I cut out a wedge shaped thick cork gasket and fill the slot.

 

If there's a small amount of gas in it, tilt one corner down so you can get a smallish dia hose in to the puddle through the gauge hole, syphon out the remaining gas and plug the hole with a rag, then flip it over..