A camp cot and backcountry gear is the simplest way to convert a minivan into a poor man's camper. Mazda MPV for example. Jetboil for cooking. Put stuff in bins underneath the cot. Swagman bicycle racks. Canadian Tire compact booster or powerbank. Backcountry air mats. Sleeping bag. Bug screens. Food in sealed bin. Cooler and buy ice. Hang gear from handles.