I wonder how the added weight of the liquid causes a performance loss or excessive wear on the ground drive parts, HST etc
If those parts are fragile they will likely fail anyway, if not a few hundred pounds likely won't accelerate wear significantly, i.e. not getting stuck saves wear on almost everything.
Here's an odd rule of thumb, for any given tractor with R4 tires (which hold significantly more fluid than R1s) a 75% load of Rimguard adds about the same as a backhoe and subframe.
The difference is that fluid in tires isn't "carried" by the tractor, it is somewhat akin to pulling the weight on a trailer, except you don't have the additional drag of trailer wheels
Rough guess; Your tractor with R4s would take about 1200 lbs of RimGuard.