1992 Polaris Trail Boss 250 Disassembly

New to Forum! Have 1992 Polaris 250 Trail Boss, Model: W927527.
New to do top end, compression only 78psi. Wanted to remove body parts, ie. front fenders, but the oil tank has to come off before the fenders. Seems the oil tank is riveted to the frame. Is there a trick to removing the front fenders without drilled out the rivets? If not, whey would a manufacturer use rivets on parts requiring removal of the part or associated parts?