The first 2 photos, I built 2 boxes from scrap 5/8” ply with 14Ga aluminum sheet sides. I used aluminum on the sides as it’s lighter and gives more internal storage area. The boxes slide in aluminum angles screwed to the floor. The intention is to load the boxes in the house or take the boxes inside when we return home making packing easier. We actually throw our food in the boxes on our clothes when emptying the trailer when we get home. The boxes do get a bit heavy but one person on each end, we can unload pretty quick.
The second 2 photos, the cabinet at your feet under the kitchen cabinets. Aluminum dividers are used to stop tall items from falling over like dish soap, cleaners, and cooking oil. Move the dividers as required. Again built from extra ply and pieces of scrap aluminum.