Simply going offshore will not work for you, as Belgian tax authorities are entitled to impose domestic corporate income taxes over your company established in offshore or low-tax jurisdiction. My first thought is to draw up an impeccable agency agreement between Belgian company and your company abroad (e.g. Cyprus), so that you will be able to redirect some of the funds through low tax system.
Another possibility is to move out entirely from Belgium and relocate to other country in Eastern Europe, Asia, South America.