I have this issue at a few of the campsites we frequent.
I built two out of pine. The top and bottom plates are 1x10 and the sides are 1x6. They are glued and screwed together. They are very lightweight and sturdy.
Goody Two Shoes and the Filthy Beast
2008 Silverado 2500HD
2012 Wildcat 282RKX
You cannot make things idiot proof, you can only make them idiot resistant.