All the parts are thin, flimsy and light because it is a 3D plane. Designed to hang on the prop. You might sub some lite ply of same thickness for the balsa in the tank and radio gear mounting areas. Kinda depends on how much 3D you're planning on doing. More weight requires more power to hover.

On the fuel dot thing, same as what Ken said and also keep carb fully closed during fueling to minimize fuel coming thru it.