Complex sentence: Regulating the lucrative trade between the monopolies on either side gave the Hoppo great leeway in setting and collecting tariffs and fees, which were substantial, and the additional surcharges, bribes, and customary fees enabled him to send even more substantial sums to Beijing.
Split into simpler sentences: Regulating the lucrative trade between the monopolies on either side gave the Hoppo great leeway in collecting tariffs and fees. The official revenues were substantial, and the additional surcharges, bribes, and customary fees enabled him to send even more substantial sums to Beijing.