How to tell doneness of a boiled egg besides time I live at 7000 feet, so when I want to make a soft-boiled egg, I either undershoot the boiling time when I follow times online, or over shoot it into hard boiled by adjusting too far up. Is there any real way to tell the doneness besides time (or the obvious crack one open)?
Try an egg timer that measures temperature.

Here's an example (that I don't necessarily endorse): Egg Perfect Timer

The idea is, the device supposedly absorbs heat similarly to an egg, and gives a visual signal of the level of heat absorption. If the water is colder than typical, because you're at a higher altitude, the time it takes to heat the eggs and egg timer will lengthen, but the amount of heat the eggs and egg timer need remains consistent.

I had one very similar (perhaps that same brand) when I was much younger.  I remember it being hard to read, but I think it was accurate.