I studied every cargo carrier online I could find, mostly at Amazon, then I stopped at a few shops I ran into one day, to see theirs and one shop sent me to another shop and lo and behold they had just what I wanted and were willing to assemble and install it for me too right then and there. Bingo! Otherwise I was planning to order and assemble one I liked.
I chose aluminum, a bit more pricey, but it's lighter in weight but still was rated at 500 pounds carrying capacity.
I bought an offset dual hitch with mine because I wanted my cargo carrier higher up off the ground but they make cargo carriers with built-in bike racks too. I can also lower mine back down then hang a bike rack off the 2nd hitch.
Good luck and keep looking until you figure out what you want and what works. I went with a 500 pound carrying capacity, figuring it would be stronger even though I don't carry near that much on it.
I watched a funny guy in a campground on the lot next to me unload SIX bikes off his cargo carrier, and each bike was a different color and size (4 kids and small wife). It was funny to hear him count them as he unloaded them then finished by saying 1-2-3-4-5- SIX bikes! Cool! I didn't lose any!