We are using this one. It seems to do a pretty good job. My wife wishes it had a setting as it will work almost too much when we re-gen then trickle off to a nice treatment for the next few weeks. We’ve been using it for about 1.5 years now.
I also added a whole house filter before this but after the pressure regulator on our setup. Both just sit on the ground outside of the utility cabinet.
https://www.rvupgradestore.com/Porta...-p/88-2130.htm
You’re question reminds me that I need to get a couple pounds of salt as we’re out in Palm Springs now and the water is pretty hard.