Interesting, never thought to that. Are you keeping it on city water? What water test results do you have? Iron?
Since this is an upflow unit, a pre-filter is required and must be maintained.
There should no-to-very-little iron in the water.
Yes, you could put resin in all tanks. Double the salt dosage (1--2lbs.) and a double the total hardness disc setting. Monitor hard by testing water and an adjustment may be needed.
The gaskets should not be replaced. Use only silicon grease and never petroleum oils like Vasoline.
Brine tanks need to be set for metered not timered electronic settings so you would need a Kinetico brine tank and float setting for 2lbs.
Put on the right conditions and settings, I see no reason why it shouldn't work.