Food
Having air tight and water proof storage containers will be vital to keeping critters out of your space and keeping food fresh. When it comes to keeping items cool, you can keep it as simple as a cooler with ice or as complex as a solar panel system that can convert power to whatever adaptation you need. It all depends on what you want and need for your trip.
Medical
Having a basic first aid kit is of benefit to your overall systems. It's good to have everything from band-aids, to thermal blankets. You can build your own DIY kit or buy already assembled and sterilized ones from reputable companies. Many of them have ratings and descriptions to help you choose what you need.
Clothing
Rain Gear
Layers for outdoor exploration (dependent on adventure of choice)
Layers for days with indoor activities incorporated
Set of clothing and socks for inside van only (comfort)
Emergency and Repair
Having a small selection of tools handy can be the deciding factor of whether or not you can get back on the road if your vehicle breaks down. Small mechanical issues such as a loose battery bolt, or a flat tire, can easily be repaired if you come prepared with the right tools. A few things we would recommend in addition to necessary tools; a simple flat tire repair kit, wheel jack, small back up battery with jumper cables, and a spare tire if possible. Small mechanical issues such as a loose battery bolt, or a flat tire, can easily be repaired if you come prepared with the right tools. Otherwise, you may be stuck for longer than you anticipated, and with extra fees.
Water
We recommend having three days of clean water on hand as you travel if your space permits. This will save you time, energy, and money to not have to fill so often. Having containers that can experience many different temperatures without there being bacteria or material breakdown issues is essential. Having a couple larger containers and smaller water bottles to refill seems to be helpful while traveling.
Cook and Clean Wear
Whether you want to have all cold foods and snacks when it comes to cooking or you are an expert outdoor and stove cook, having some organization will be helpful. Having a small dish washing kit prepared and some containers to store pans and utensils makes meal time way less of a hassle. Take some time to imagine how much time you want to spend on meal making and what kind of set up you might need.