I am on a well that after softening has .5 ppm iron. I would truck in the water.
There are a ton of things you can do to mitigate iron/staining. They're all quite expensive over time, and stains will come back every time the sequestrate exhausts itself, or the ph rises a little too fast, or the owner forecloses and innocent lil ole me buys the house
If you truck in that first load of water, then you won't be as snookered if you forget once to pre-filter the water, for example, because the amount going in the pool will be diluted.
I would hazard a guess that a season of jack's magic pink stuff, ascorbic acid stain treatment, and hose pre-filters would cost more than the truck full of water, although I know it's not cheap. Also, at some point, historic staining just doesn't completely go away, which for some people, might prompt the desire for a new liner a few years before it's otherwise necessary. The nanosecond I replace my liner I am trucking in water

So that's my vote.
But see what your reads are. Do you have a water softener for your house? Do you get any staining whatsoever in your dishwasher, toilet, etc? If you do, truck the water
