Most RV antifreeze is propylene glycol and ethanol. Both of these molecules are considered polar.
Garlon 3 should dissolve in RV antifreeze. Garlon 3 is an amine form of Troclopyr. It is a polar molecule, so it should dissolve fine in ethanol and propylene glycol. The ester form of Troclopyr should dissolve in alcohol because alcohol has a polar side and a nonpolar side. The ester form of Troclopyr would dissolve better in diesel.
Arsenal is amazapyr, which Google says is polar. It should dissolve fine in water, alcohol, and propylene glycol.