I use a water softener, but I dont have an extra. I have noticed a big difference in how much less cleaner I need to mix. I have one at my house and fill my fresh water tank every morning and then swing by the house if needed during the day.
Buy a resin in brine unit, (all in one unit), can set it up to recharge right in the van, connect to a water source, an extension cord, and a hose from the brine rinse to a drain. Connect those three things, hit a button, walk away.
You can buy 30k grain units at your local plumber supply house for under $600.
We used to rent, however these guys virtually never need maintained and last for a looooong time.