I know that there are some fairly heavy plastic square made by Keter at Lowes or Home Depot that might serve your purpose. The one thing that would give it greater stability is having the proper leg placement and feet, weighing more, and being more square than rectangle. The Black and Decker uses legs like a TV dinner stand, is pretty rectangular, and is pretty light which is why I generally brace it against a wall or some other substantial backdrop
I also have a woodworking plans book that has a workbench that is shallow and mounted to a wall with a hinged worktsurface that folds out in order to minimize space. With proper bracing, that would be a pretty heavy duty solution. I am sure that you could find plans for something similar on the internet or some other folding type workbench surface. One other trick is to build a potting soil type bench outside which can double as a worksurface or even a wood picnic table can suffice. My reloading bench which is very heavy is made with polymer legs (2x4 basics is the brand name for these), 2x4's, deck screws, and heavy 3/4 inch plywood decking over the bracing Only straight cuts needed and it can be sized accordingly. Good luck, I am sure that you will find a solution that works and fits the space needed.