I used to use one of them small galvanised ones. I bolted a piece of ladder across the top, front to back, this was used as a kind of roof rack for my trolley, and it still left enough room for my 10 containers and battery box underneith.
I now use a small box trailer, and again I'm making a rack for the trolley, I'm also putting a hole through the front so that I can put the poles inside, trying to avoid carrying any cleaning stuff in the car.