Editing Geometry

Has any already tried to make custom geometry to send to TMP? Looking at the docs the info isn't very concise of what I need to set where and I can see in the shader multiple UV channels are used which gives me some hints.

What I am hoping to achieve is garbage free rendering in certain situations (timers etc). I can get it really low with SetCharArray but hoping UpdateGeometry can get it to 0 (depending on the internal code ofc) and don't want to spend forever learning the geo structure just to test this.