you could.. but how to shut off fuel?
a petcock is a valve .. normally has three setings, on, off and reserve.
"On" or "Main" means fuel is entering a short tube that extends up into the tank a few inches..
When fuel level drops below the top of that tube, you must switch to "Reserve" to drain the rest of the tank (gives you time to get to a gs station). Reserve fuel feeds into a hole on the petcock body.
Off is self explanitory .. the Main tube and Reserve hole are protected with a wire mesh screen.