Well, to answer your first question, I would expect nothing less from a badass super smart off grid person than to share their worst failures, and most stupid mistakes! There's no shame in admitting to them, and it may be highly valuable info for other aspiring badass super smart off grid people.

As for mice, believe me, it could get worse... or let's say smaller! Have you heard of the damage bedbugs (as well as probably many other kinds of insects) can cause to electronics? So even if you manage to make a place entirely mouse-proof, other critters might still be able to get in. So what solution can I suggest? Hermetically sealing off a place can be super hard to impossible, which means you won't get around monitoring carefully and regularly. (Even then you could miss things, which is likely what may have happened.)

As for the shipping container, those things can be amazing (I'm a big fan of them), but they also heat up quite fast. Have you thought about berming them up? Of course, that involves moving a bit of dirt around, but it makes a world of a difference, especially if you dig in the southern side. Another option would be letting plants cover the thing, but that may not be entirely viable in your climate (scorching days and freezing nights I guess), and in any case it takes time for them to grow.

Anyway, thanx for sharing!