A lot of different meaning in the word allegedly. Down in Louisiana where I farmed with my Dad till I was 24 years old and where it seldom gets cold enough to freeze a tire solid, we used pure water and always filled the tire a bit over full then with the valve stem at 12 o'clock, drained it till we had just air coming out. That is considered 75% fill. Never had any issue with highway travel, dont have a clue what you mean by power hop and have pulled drawbar pull implements all my life usually putting over 1000 hours per year on each of our tractors. If you mean the tractor tire jumping then gaining traction, slipping again, then more weight would lessen that effect better than less weight.
We always had our Ag tractors fully ballasted with water in all tires (front and rear), full sets of front and rear weights which usually equated to around 1000# in front and about that much on each rear wheel plus running duals on the rear when using ground engaging equipment. We never had power hop as you call it because we had the traction to prevent slippage to not more than 5%.
Actually I could see how 50% fill might cause more problems with liquid sloshing in the tire than a 75% fill since you have less air space for it to slosh in. Mostly the liquid just stays put and the tires rotate around it, pretty hard to make water run uphill but beet juice just may tend to a bit more than water or water/antifreeze mix.