It's not a happy picture. If the tire fill is indeed Calcium well darn and I'd be as careful of that as I would antifreeze or dumping drain oil on the road for dust. It just doesn't happen here.
At the same time I have my toy tractor and big bertha filled with CC. I do that for a reason: it was what the vendor supplied, it was economical, and the
ballast has saved me more times than I deserve. Safety is 1st.
So you have a leaking tire on a small tractor. If you dismount it do you not have another way of getting it (both) into your pickup? No neighbor with a loader?
Whether you do CC or something else I am a true believer in ballast. After these years you are also used to it and you probably don't want to run without or you will be learning new lessons and still calling your neighbors - hopefully you survive the problem.
I like the earlier suggestion of a tube. Yup. Frankly I like tubes anyway. I wish you health and safety.