It is ironic that you seek TCMA truth through the internet, while you refuse to take the word of someone practicing a lineage of Wing Chun that addresses the ground fighting scenario.
Also, I have the
proof. It is you who doesn't have it, so you are the one who should search for it, that is if you have an inquisitive mind. My only advice is that you will find it by dedicating yourself to practicing a REAL and AUTHENTIC TCMA, and not the majority "fast food" versions that most people, including those who post on internet forums practice.
Alterantively, if you do not have the patience, nor the desire to research and practice the TCMAs as complete arts, then your local BJJ gym is your friend.
To each his own, I say......