You can use a large magnet as a tractor counterweight to balance the weight of heavy loads.
Use a Tractor Counterweight Magnet for Heavy Loads
I needed a counterweight for my tractor to keep the front end on the ground when pulling a heavy load. My neighbor gave me a 50-pound magnet that I thought might work. And it does! I also use it for carrying tools around. I just stick them on and they won’t fall off because the magnet is so powerful. You may be able to find a magnet like this at a junkyard or flea market.