Just vassalize SE Asia, Korea, and Manchu and you should be alright. Let Ming beat up your tiny vassals while you take over the lands near its capital. If a giant deathstack comes after you, run away, load your troops back on their ships, and sail them somewhere else to attack. Keep that up for around 5 or 6 years and Ming's war exhaustion will skyrocket, revolts will spring up like weeds, and Ming will soon enough collapse into the inveitable Ming/Wu/Xu trifecta.