Dump truck here too. 1 Ton w/ 8'x 12' bed. 2' high sides. and still wish I had more room a lot of days.
I use a walker with the dump bins too. But I get them into the truck reguardless of their weight. haha! I can tell ya, cutting not a lot off, on a dewy morning, will PACK that hopper. I'd guess those bins weigh over 100 lbs each. I also have a grasshopper with the 3 bag catcher. Bag type catchers are the easiest to work with/dump into a truck.