score:4
You are thinking in terms of luggage. Think in terms of packages.
UPS, FedEx, DHL and the various national post offices each have a mainline business of shipping things, predominantly in cardboard boxes. They have rules for shipping durable things which are not in cardboard boxes, e.g. Automobile tires, steel sections, etc.
They also have weight limits in the 20-30kg range, with surcharges above that, because OSHA and other nations' rules require special handling to reduce worker injury.
So rearrange your packages to be within their limits, to discard/donate/sell that which does not need to be shipped, and to segregate things for purposes of Customs, e.g. "All things purchased in USA". Items which require a duty be paid on them, should best be taken with you on your airline flight, and paid at the Customs desk.