When it was time to change my in tank fuel pump, I looked around the garage an found the straps that I used to secure my dirt bikes to the trailer. Hooked 2 straps to the frame on each side and then hooked the straps together under the tank. Undone the bolts an metal straps holding the tank up and lowered the tank with the bike straps. They worked equally well to lift the tank back up. No jack or lumber required.
You may have to lower one side of the tank more than the other to clear the frame with the filler neck.
Richard