As noted by some, it is important to select a good floor plan to minimize setup hassle and maximize the hauling capacity of the trailer so as to avoid over-packing the minivan.
The relatively low tow capacity of the van can help in this regard, since you won't be choosing a slide-out model. Those actually badly constrict accessible interior storage volume.
My tips:
1. Store folding chairs permanents under the dinette table. We fit 5 there plug a folding table.
2. Buy a Sterilite 2 drawer plastic box (about 2' wide and 3' tall) for dry food storage. Bonus, you can load it in the house, carry it out and lie it flat on the pup floor for transport. Stand it up on the county when setup and all your food is out of the way.
3. Cooler rides in the pup for the trip, then moves to the van hatch for storage at the site.
4. One person, one duffel bag. They all ride in the trailer. No extra loose clothes. Fit 'em in or leave 'em home. No exceptions, kids! Duffels move to dinette table before bed and move back to bunks after wakeup.
5. Kid sleeping bags and pillows live permanently in the camper in a dinette bench for transport and storage. Mom and Dad's duvet stays in and sheets and pillow cases get washed after each trip.
6. Large flat Tupperware holds all utensils, stores/travels in the trailer and moves to the picnic table upon arrival. Virtually all eating and cooking is outside. This IS camping, after all.
7. Dish pans and dry racks ride under the sink, but stay outside upon arrival. Except bear country trips (We're Midwest folks).
8. A thin rug just inside the door helps minimize dirt tracking a lot. Shake outside twice daily and use a welcome mat for wiping feet OUTside the trailer.
9. Bench storage is an access hassle. Use that space for things that come out ONCE and stay out until it's time to pack up, if you can. My outside stove and water heating kettle are good examples.