Rimguard is beet juice and non toxic, Anti-freeze is very toxic. It shouldn't be used if there are other options.
CORRECTION; automotive antifreeze in most cases is ETYLENE GLYCOL which is deadly posion that disrupts and destroys kidney and liver function, ingesting it will lead to a very painful death. (note; I sell thousands of gallons of propylene glycol inhibited with anticorrosion additives for HVAC systems in schools, hospitals etc. So that if something happened to leak and anyone drink it, would only give them a bad case of the runs.)
That said the RV antifreeze is usually NON TOXIC PROPYLENE GLYCOL, but READ THE LABEL. Propylene glycol RV antifreeze may contain some anticorrosion additives, but will not kill you, might make you very regular for awhile. READ THE LABELS.
I used windshield washer fluid in my CK20, works good but is about the same weight as water (8.34 lbs/gal). Next caution is most windshield washer fluid is methyl alcohol (sometimes known as wood alcohol and is poisonous).
My new CK2510 the dealer loaded the rears with RIMGARD (11+ lbs/gal). I have noted some "lumpiness" on the road in high gear, when temp in the 20's.
Can't wait for snow in Rochester NY, to try out my CK2510 cab,heat,stereo, and front mount snowblower.. Yahooo!!