X 2 on filling, I just saw that you are in Florida so no issue with freezing so you can use tap water to fill with so really cheap ballast.
Filling those big Turf tires will probably give you enough weight for most operations without anything other than maybe the box blade. I like to have the box blade on mine anyway to us as a bumper. I have trouble looking behind me without turning in the seat so the box blade stops me before I run over something to damage the tractor.
If you are worrying about rutting with loaded tires, dont. The weight is spread out over such a large surface area that I doubt you could tell the difference in tract.
Second, those turf tires look like a well inflated baloon and about 1/2 the tire profile is all that is touching the ground. Let some air out till they squat a bit. With that size tire, that is going to be around 8-10 PSI or or even less. You will gain some traction and decrease the PSI ground contact loading.
Even if you decide not to ballast your tires, set the correct air pressure, you will be amazed at the difference in ride and traction.