Well, keep this in mind: I knew quite a few people who got interviewed with, and arrested by authorities. Everyone under the age of 18 in the 90s got a slap on the wrist because they hadn't got too good at punishing those kinds of crimes. I think the worst I saw was $1200 paid over 12 months to AT&T.

After 18, you're done, even if they can't think of a good charge, they'll make them up, which is exactly what they did back then, cross state commerce was a blanket thing to grab folks.

I stopped doing anything questionable well before I turned 18.

Eh, it's worth it, depending on what you're doing. I'd much rather get in trouble for a hard drive full of zeroes, than them knowing what was on it beforehand.

Today, you should encrypt everything, and cut power before physical access is obtained. Will that count as "tampering"? I was just turning off my computer. No, I do not remember the key.

Looking back, federal authorities really only came when they had the evidence they needed already, and local authorities were way too far behind to know what was going on (in the 90s).

In practice, the only real protection we had (those of us in my social group) was that we were minors, and lucky that laws hadn't caught up yet.

Surely it has to be actual evidence before you "tamper" with it.

If I delete a file on my computer today that would be potentially "evidence" if seized, and the police come knocking tomorrow, I haven't committed a crime by using my personal computer in the past.

I do not suggest that you test this theory. Your optimism seems wholly unwarranted here, knowing what we know about the federal prosecutors.