what I don't understand is, what if I took a photo of the label of the 3KG (or 500g) satchels with the address and the tracking no.

Why can't it be a proof of shipping?

What a good idea.

I will buy a couple of dozen satchels, write the addresses of my customers on them, take photos, tell the buyers their items have been sent, successfully defend 24 item not received disputes using the photos as proof, re list the items then stick some address labels over the satchels and use them for sending the next 24 items (actually the same ones) when they sell.

Genius