Theoretically you could mount your own custom-made cargo box on the arm of the Yakima EXO Swing Away Enclosed Cargo Carrier - 2" Hitches - 10 cu ft - 100 lbs # Y62VR, though I do have to note that any alterations will void the carrier's warranty.
I do understand having a concern about the weight, but so long as you have the right hitch and don't overload the carrier, this won't be an issue.
Your 2005 Honda Element has a pair of Class III trailer hitches with 2" receivers that fit, the... view full answer...