It may be a little too late to suggest this, but I still hope Paradox can increase the cost for oversea wars, making oversea wars more expensive (and more difficult) to fight, such as to rule out small countries fighting oversea colonial wars in Asia and Africa (otherwise they'll risk bankruptcy and failure because of the high military cost). This can help to model why Italy could win the Italo-Turkish War in neighboring Libya, but failed the First Italo-Ethiopian War in remote Ethiopia. After all, fighting a war in your "neighborhood" is logistically quite different from a oversea one.