This is exactly what I do. After emptying the boiler with the hot water wand, machine off, there will be enough water remaining so the mineral issue should not exist.

Hello, I am a new member but wanted to comment on my experiences with water quality. Pure water is such an amazing surfactant that will attach to or 'leech' anything it can find, almost as if it's unstable when pure. While many recommend anywhere from 90 to 150ppm TDS for making espresso, with much experimenting I have found that 50ppm TDS minimizes scaling yet still appears to have little affect on flavor or metal leeching. Testers are inexpensive. With a little ingenuity you can buy distilled water, remineralize and balance the pH, making your own 'perfect' water.

I make it a point to occasionally refill my steam boiler with distilled water (well actually 0 TDS water from a zerowater filter) to prevent scaling. I don't regularly use the hot water tap, so the only "exit" from my steam boiler is more or less pure steam, leaving all minerals behind. Meaning even a small amount of initial mineral content would build up over time. I don't worry about corrosion because I figure there is a protective layer of scale in there already. Not to mention that the boiler refills itself from my reservoir, which I keep at around 80ppm TDS. So it doesn't stay filled with pure water for long.

You would have to have very pure water for the boiler level sensor to malfunction. YMMV, but It is not a problem I have ever experienced.