I carry about 10 suitcase weights on my box blade as illustrated above. Have done this for some time....but added a few more this year. I've got mine on a King Kutter box blade. Never had one bounce off yet....and I cover some pretty rough ground. The extra weight and fluid in my tires keep the rear end safely on the ground.
I also have a receiver hitch on my box blade. I have a HD, reciever-mounted, expanded-steel "box" which I had made to put on a 4 wheeler (to carry bear bait pails) at one time. I'm going to mount that box over the top of my box blade using the reciever hitch. I'm going to mount it "backwards". Should be good for extra 100 lbs of weight and will haul a HD log chain, chain saw, and tools. May mount it today....and I will snap a pic.