If you have access to cast iron weights you can come up with a setup to pick up on the 3 point. This is what I did for a smaller utility tractor I use to push loaded wagon around with front hitch to compensate for removing the fluid from rear tires. 
Depending on size constraints and amount of weight needed you could make a steel box and fill with concrete. There are also places that utilize rear counterweights off excavators mounted on 3 point. I think K&M Tractor has 3 point brackets that some of their heavy rock boxes attach to . Referenced in some other threads along with other ideas and designs. https://talk.newagtalk.com/forums/thread-view.asp?tid=605133 https://talk.newagtalk.com/forums/thread-view.asp?tid=502402 https://talk.newagtalk.com/forums/thread-view.asp?tid=47655 https://talk.newagtalk.com/forums/thread-view.asp?tid=501371 | 
3 Point Ballast box for 7430 Deere
