We used to have a short bed camper, and we used the hitch receiver cargo carrier, worked great as a step/cargo carrier. We stored our generator, and a variety of other items along with using it as a step.
https://www.amazon.com/MaxxHaul-70108-Aluminum-Carrier-Receiver/dp/B008CE0LIC/ref=sr_1_6?keywords=receiver+hitch+cargo+carrier&qid=1580854075&sr=8-6
https://images-na.ssl-images-amazon.com/images/I/41rJxpyx5gL._AC_.jpg
cheap, easy to use, (get the Aluminum one ) unlimited options on what you can do with this, adding boxes, steps what ever.