I own a Hitch Haul brand, the Al. model specifically. It has worked fine for me. I think it is sorta cheesey in construction, bolted together and a bit limber. But, it has never failed, I have carried as much as 350#'s of softener salt on it for 10 miles, it is rated at 500#'s I think but wonder who would be hauling pig iron on it. The salt was hard enough to stabilize.
If you are pretty serious about this I would look for welded construction. Secondly I would want some sort of rail about 4" - 6" high around the thing. I added taillights to mine because occasionally I will load some wide stuff on it.
I had a second unit built for me at a small fab shop to carry a portable fish house on. I needed more clearance, both height from ground and from back gate of the Expedition. I believe I paid $75. If you go this route may I suggest you have the platform sized to fit a large cooler perfectly. This makes a good bin to load dry bulk "stuff" into, and of course cooler use. If you think ahead the height can make a table for tailgating. Also think ahead about swinging the tailgate, an inch here or there might make the whole unit MUCH handier.