A bag of holding

We’re travelling at the moment, driving up the east coast of Australia. We started in Melbourne on a cold ten degree Celsius day. Now we’re at the Queensland border and it’s a lovely sunny twenty-six degrees.
It’s always hard to pack for weather extremes. Not that this is really extreme, but one is jumper weather, the other is t-shirt weather, and winter gear always takes up more room than summer. Luckily we’ve got the car.
I want a bag of holding to hold all my clothes. That is, a bag that holds more on the outside than on the inside, and that doesn’t weigh much at all. Good bags of holding can be as small as a ring, or larger, like a backpack. They can hold anything from a large box of goods to a room full, or more.
Wouldn’t it be amazing for travelling overseas. (Although, I do believe that authorities can look with suspicion on travellers carrying too little luggage. Maybe a light suitcase for any overseas trips. )