How do I start of right as Ming?

So I have wanted to try out playing a Ming but the guides I have found aren't very helpful:

1 The "Restore the Old Borders" mission seems to be impossible to do in one go and not really worth it. A full annexation take 109% war-score and the Dai Viet tradition make coring the country cost more then 1000 scrolls.

2 I have read that diplo vassalizing Haixi and Jianzhou should be pretty much a done deal as Ming of you start working on it right away. But seemingly Ming has a smaller economy then some step hordes because I get a -70 " Ming economic bace compared to Haixi/Jianzhou" penalty when trying to vassalize. This is before either of them has taken any land from their neighbors.

So what should I be doing. Try to diplo annex smaller hordes or something else that's clever?