Can fuel be stored in the anti-shock bodies?
Yes, and there have been cases of this. Tip tanks of the period when aircraft flew already supersonic and jet engines were still very thirsty are a good example. Below you see the area-ruled tip tank of the F-5.



F-5 tip tank (picture source).

Now that @voretaq7 got me thinking, I should also mention the "Doppelreiter" fuel tanks (slipper fuel tanks) which were used on some German fighter airplanes in WW II. They were mounted above and behind the wing, and to everyones surprise they had little impact on the top speed of the airplanes, and in case of the Me-309 helped to increase it slightly. They were the first practical application of Küchemann carrots and worked much like the flap track fairings of today's airliners.



FW-190 A with Doppelreiter tanks.