I've sort of lucked out with salt. The salt accumulation seems to be a wash with the water that is replaced naturally due to rain. I actually had to add a bag a while back. More on that in a bit.
My fill water is about CH:350. I control CH accumulation by topping off the pool with soft water (CH:0). I dug up my auto-fill line and re-plumbed it to my house's water softener. I've been maintaining a CH <400 for several years now.
I have a PoolMiser auto-fill system, which houses my overflow exit point. The small well this system is in connects to the pool via an equalizer tube that enters the pool a few feet below the surface. This is theoretical, but I believe this is what's happening: When it rains the fresh water floats on top of my saltwater pool. With conventional overflow systems, like a hole or grate in the edge tile or skimmer, a lot of the fresh water would drain right off the surface. But because my equalizer tube is well below the surface, the fresh water rain forces the salt water out of my pool from below, allowing the fresh water to mix in. Every time it rains, I'm getting a mini no-drain water exchange, and it is this effect plus the water softener that is keeping my CH and salt accumulation in check.
Additionally, if I test and find elevated levels of salt and/or CH, I'll manipulate the rain water exchange. Just before a prediction of heavy rain, I'll use the overflow tube in my PoolMiser well to lower the pool water level a few inches. The rain replaces the drained water, and that brings down the CH and salt even more effectively than what I described above. I lose a little CYA in this process, but that is a very small price to pay.
So it's three MOs at work.