Grow potatoes in a double planter Saw this on Facebook. Looks pretty easy to do. Buy two planter buckets that will slip inside each other. Save a tater that has started to sprout, cut the "eyes" off in good sized chunks. Let the cut sides dry out for a couple of hours. Cut the sides off of one of the planter buckets. Slip it into the other planter bucket. Fill with a good soiless planting mixture with the water crystals added or add your own. That last sentence is the key to container gardening. I've never did tater in that small of a container. The largest I have done was a 55 gallon drum. The smallest I have done was a 5 gallon bucket. One squirrel in the whole park and guess what they found. Small taters (like the reds and the golds) are best for small container gardening. Compact vegetables are what you need to be looking for. Bush green beans. Patio/bush tomatoes. That sort of thing. Look for a container gardening forum on the 'net.
Keep in mind that bugs (ants & roaches in particular) love container plant containers.
The Rubbermaid Plastic Vertical Outdoor Storage Shed, 18-Cubic Foot is 3'11" wide and can be mounted to the rear doors of a van. top of rear bumper of a MH etc.
You would open it up during the day to capture the sunlight facing due south. This would be best suited to a hydroponic grow medium using Rubbermaid totes as growing vessels with 2" dia net pots cut into the lids using rock wool to anchor the roots.
You will need a small inverter to run the air pump, I would also run a small submersible water pump with a little pvc manifold that constantly squirts the hydro nutrient solution against the walls of the vessel that splashes the roots above the water for maximum nutrient absorption.