I think what people have been trying to tell you is the opposite.
Zheng He is NOT the best for it. The purpose behind and the parameters of his missions were not missions of discovery nor where they colonial in nature.
If you want extensive Chinese colonialism, you need a deeper POD. One where either the extensive Chinese merchant networks take a more active political role in their host countries, or one where China is interested in actually colonizing (and not concerned with the steppe or internal unrest).