There have been a couple threads posted where wheels failed with spacers
+ liquid in tires
+ iron wheel weights, in triple combination.
OP specified he needs to mow
across slopes. Strain on downhill wheel will be heavy, perhaps double strain on level ground, perhaps MORE. Add tire liquid and cast wheel weights and there will be a very heavy load on downhill spacer. Should tractor begin to roll, liquid tire
ballast will shift, making roll inevitable.
This is a SAFETY issue with potentially mortal consequences. Not prudent to explore close to boundaries.
OP's
"B" has a lot less beef than your
"L".