I built my own dump carry-all about 15 years ago. You can't back into a pile to load, but had other attachments to do that. This was built to do rock pickup in the fields, haul dump firewood, hauling manure out of horse stalls, to be dumped in my manure storage bin, haul bales of hay, fence posts and tools etc. I basically copied a bale carrier frame, then added the dumping platform. I calculated the dump cylinder location, by measuring the cylinder set up on my 1-ton dump trucks cylinder position, then scaled it to fit this. I used a 2-1/2" cylinder, and it has yet failed to dump anything I've put on it. I did make the deck from 1/16th sheet metal, which has held up well.
When building my new buildings at my present location, I used it as weight on my 180 Massey, to compact the fill material for the base's. I backed my dump truck up to it, and dumped a load of the bank run material I was using for fill on to it. What stayed on, was the weight I worked with. I'm guessing it was between 1,000, and 1,500 lbs. When I was finished, I dumped it off, and it dumped it effortlessly, with the 180 at idle.
I later added a hydraulic top link, which allows you to tip it forward to keep fence posts, etc., from rolling off the back. It also allowed tipping back, when dumping something that may have a tendency to stick to it, like wet manure. Or, just backing up on the pile a bit, and make a greater angle of dump position.
I don't use it as much as I did back then, but still is the perfect attachment at times, for certain jobs.