It could work with a 3 Point Johnny bucket type set up but you are talking about investing considerable money. But if you are talking about doing this with a standard "pond scoop"/dirt scoop, my personal experience is that you really want it to be able to dump so the bottom of the scoop is at least at a 90* angle to the ground to be able to effectively empty the scoop with anything damp, clumpy or wet. Similar to the dump angle in the picture of the big John Derre with rear bucket. The first implement I bought was a 30" "pond scoop" ( dirt scoop) and one thing about the trip mechanism is it is quick and the pivot design allows the scoop to pivot past 90 degrees, which I have found to be really efficient when unloading most types of material. Pull the trip while reversing and as the bucket begins to empty the bucket lip digs in a little and you keep pushing backwards until the bucket bottom is past vertical. Pull forward while lifting the 3PH and the bucket resets itself. Very simple but also much faster than almost any hydraulic cycle time. You can dump a load and be on your way back for another load in a matter of seconds with a little practice. The only advantage I can see to using a cylinder is to limit the dump angle better for spreading or partially unloading the scoop...but you can do this with a standard rope trip type as well by adjusting the 3PH lift height, however a cylinder would let you do this with the bucket lip off the ground, which may give you better control in this situation.
A standard dirt scoop will gathering and dump loose material like no ones business. For such a basic and simple device, they are very effective, not to mention cheap ( $150 will find you a nice used one all day long). I got rid of the trip rope on mine and ran a length of #40 chain from the trip mechanism to a spring loaded lever mounted on top of the frame. The lever is long enough that it was within easy arm's distance from a seated position and offered good leverage on the trip mechanism.
The bucket shown on the Honda tractor is really nice but just a glorified example of one, it even uses a rope trip mechanism if you look closely. I also guarantee that at that distance behind the tractor, a full load of sand or dense dirt would have the front end of the tractor off the ground when you lifted the bucket.
Prior to building my FEL, I used my scoop quite often and have moved many truck loads or dirt and rock with one. With 230lbs of front weights on a FWD tractor fairly larger than yours, I could still get enough clay in it to make steering really "iffy" without using the wheel brakes.
Hydraulics are cool and usually the only way to go but I think this is one of the few times that it would be more effective to not use them.
BTW, EXCELLENT score on the Yanmar! You're certainly an impressive young man.
