Being you're limited to weight, this probably won't work for you, but maybe others can get some ideas, if they want to build their own. It has a multitude of uses, from easily hauling 8 bales of hay, to cleaning horse stalls, and dumping on a pile, picking rocks up out of a field, and dumping in a wash, with out leaving the tractor. Hauls a good bit of firewood, and I can stock a good sized pile making several rounds, dumping in a pile, to be stacked later. I even used it for weight on the back of the old Massey 180, using it as a roller to roll the fill for the horse barn, and shop. I just backed my dump truck up to it, and dumped a load of fill material on it. What stayed on was my weight. When I was finished, I simply hit the hydraulic remote to dump it.
It's definitely earned it's keep around here, and sure has saved a lot of work, and time.