I went without for years until we spent several months at an RV park with very hard water. The softener took care of that. The negatives are the backflush and regeneration labor and the space needed to store the unit when traveling. Happily, the table salt does not cost much.
I bought the On-the-Go Double from the manufacturer (link here
). At the time the price was the same as through a third-party seller.
Some folks (such as "Dutch Star Don") have installed their softeners permanently, e.g., inside a storage bay. I recommend if you do this that you build a system to eliminate making and breaking the connections to backflush the unit.
Also, you'll want to think through filtration and pressure.
If you have water filters, you need to decide where to install a softener. I've seen recommendations to put all the filters ahead of the softener. My coach has a two-stage filter inside the wet bay. It didn't make sense to move that. So, I decided to add a single sediment filter (30 micron) between the hose bibb and the softener.
The same RV park had water pressures at the bibb in excess of 100 psi. I felt uncomfortable exposing the hoses and softener to that high a pressure, so I set the regulator at the bibb for 60-65 psi and let the (permanently-installed) regulator in the wet bay reduce that to 55 psi for the house.