The "secret" is to have a lot of small bags to stuff into corners. The large bag on the bottom right fits like a glove behind the seats, and is almost locked in place by the lip on the seat backs when the seats are folded down. The smaller luggage fits in the trunk, and everything else is packed around it in the small areas.
This is from 2022, our trip to the Poconos. You can see my wife wanted new luggage, so now we have new luggage. Happy wife = happy life.
The other photo is from Savannah, GA back in 2011.