Bring those princess dresses! Those precious memories will never come back, which I’m sure you know that already 
. Bags and duffels fit better in cars than suitcases. Tie those sweatshirts and jackets around waists. If you want to save the money, just squish it all in for the semi short trip to the vacation rental. Or have DM and DSis take Uber to free up some space (still cheaper than renting a bigger vehicle). Returning to the airport, we are always fuller…
Don’t you have a campsite reservation you could use to get a couple of people on DME? Maybe Grandma and the little girls could enjoy the campgrounds while everyone else takes care of the luggage in the minivan and you could pick them up later.
We have overspent our budget on vacations. We tighten our belts when we come home. Miserly eating and other habits for the next month will help bring us back to budget.
We didn’t fly for trips until the kids were 10 and 12. It was always road or camping trips before that. If it fits in the Odyssey, it’s going! The first time we flew, we had too much luggage to fit into the CAR (not minivan) at our destination. We had 2 medium, 3 carry ons, and 4 personal items. But, we were too cheap to pay for a bigger car. The trunk barely fit the 2 medium suitcases. We stacked the carryons between the two kids and we carried the personal items on our laps or next to our feet. (It wasn’t as bad as the time we had 7 people and luggage in the Caravan.)
The next time we flew, we packed smarter with lists. And this is were the packing cubes entered and stayed with us. We don’t do laundry because we are on vacation so we have to pack new outfits for each day and that can be problematic with mixed temperatures. Or we can just conveniently forget about the mixed temperatures and just pack shorts and tees. 
That has happened in Hawaii when the temperature at sea level was 80 and the temperature at the peak of Haleakala was 50 with a wind chill factor! Nobody had a jacket or pants!
Nowadays with car break ins being a norm, everything has to fit in the trunk. If they don’t, someone stays with the car until we can drop off at the hotel or airport. In California where we live, thieves are breaking into cars even when there is nothing visible. They go through the trunk and car, looking for anything to steal. That is where our paranoia comes from.
One year after we implemented strict luggage rules in our house for flying, we were going camping again. The kids took a huge black trash bag, filled it with their favorite stuffed animals (mind you, they must have been 13 and 15), and threw the bag in the van after DH had packed it tight with food and car camping gear. We were dumbstruck at the furry friends lining the sides of the tent after it was pitched and the car was unloaded! They have missed bringing their furry friends on trips. Stuffed animals and camping don’t work well. After our 3 night trip, the stuffed animals aired out in the garage for weeks. But those are precious memories.
That’s a small lunch for my crew.