I put bath/hand towels, pants, sweatshirts, hats and jackets under the bench.
Bug sprays, gas bottles, lanterns, candles go in one cabinet by the door.
All cooking/eating stuff goes in the galley and below it.
TP, paper towels, cleaning spray, Kleenex in the other cabinet  by the door.
Maps, books, games, shower shelter go in dinette.

I do not jam everything possible in every possible spot.
I take less stuff every time.
If I truly need something I forgot, a town or store can be found.

I find something that maximizes the space i have and put it there. 
Zero gravity chairs under the dinette
pots and utensils bottom of tilt up galley. 
lightweight stuff in top of galley
dual fuel stove in hole next to galley when down
sleeping bags can be stuffed anywhere
grey water buckets in aisle with odds and ends
Box of dry food and cooler by the door.

Clothes go in the TV with other odds and ends that are too big to fit in the popup.

We pop-up the day prior and put everything possible into/onto the PUP:

Nonperishable food, drinks, football, poker set, toiletries (rather than tote toothbrushes, deodorant, etc. back and forth from home to camper we keep a separate supply in the PUP), towels, paper towels, extra sheets, extra 20# propane tank, pillows, bike helmets, and clothing all goes under the benches.    We fill the fridge with sodas and adult beverages (beer or margaritas) and pre-chill on electric before we leave; even if we don't run the fridge on battery during the journey, it stays cold - our family ritual is enjoying a cold drink together after we are done setting up.  Paper plates, plastic bags, dish scrubbies, foil, plastic wrap go in the fold-down cabinet under the stove.  The bbq, water hoses, wastewater bucket, clothesline, beach/bag chairs, ladderball, skimboard, family collection of flip-flops/sandals, and box of cutlery/dishes goes on the PUP floor.  Beds get made the day prior also and pajamas are laid on top of beds; PUP is popped down with the beds made and pj's at the ready.  Totebag full of library books is stuffed in wherever it fits (sometimes the books are read, sometimes not).

Tackle box, bait cooler, and crab trap gets bungeed on the tongue support near the battery.  Rug gets rolled into 4" pvc pipe mounted to camper frame.  Bikes are loaded onto Sixnall bike rack that sits atop PUP and locked to rack.

The TV (08 Durango) carries our kayak on top along with fishing rods.  Inside, we have 1-2 coolers of perishable food/ice (in the very back).  We also take our 10' ez-up canopy for the beach (we fold down the rear third seat flat, and middle of back seat (DS's sit on either side)).  The toolbox is also carried in the TV along with the camper crank and lynx levelers.

Everything fits really well; I had a lot of trouble remembering how to pack it till DS suggested I take pictures of it on my phone - it really helped!