I've got a smaller tractor with the 14 loader. I have 900 on the 3 point hitch, and just finished making up 160 lb for each rear wheel. Trying it out, I picked up a green cherry log about 10 feet long and 12 inches across, tilted the bucket forward (I have a grapple on the bucket) lifted the log to about 6 feet, dropped it quickly a few feet, and stopped the bucket suddenly. The rears lightened up noticeably, I bounced in the seat, but nothing came off the ground. I tried it with the tractor at an angle up hill, same thing. Downhill quartering, same thing.
I finally drove to a spot where I could gradually drive the tractor onto a sideways tilt. I was watching everything pretty closely and it felt stable despite being leaning quite a lot -- way more than I would normally ever operate, probably pushing 30 degrees. Then I noticed the front downside tire with about 35 lb of air in it was displaced quite a bit from being centered on the rim, and decided enough was enough.
My tractor is about 2500 lb without the loader. I have slightly more than half that amount on the back end, with about 35% on the wheels and the rest on the hitch. How much you need and where you put it depends on your ground. Weight on the hitch will keep the rear end on the ground but will not prevent rolling over sideways. Weight in the wheels or tires will do both, but pound for pound is not as effective at keeping the rears on the ground as weight hanging off the rear hitch due to lever effects.