>I would expect that they can just perform hardware tampering when you're not present On what legal authority? The border search exemption is about searching,

>I would expect that they can just perform hardware tampering when you're not present On what legal authority? The border search exemption is about searching, not tampering. The issue is more that border agents are taking advantage of a law written before the age of computers to use powers the founders probably never intended. I seriously doubt that there's any legal basis to bug a computer just because it was shipped internationally. So if the threat model is being asked for your password, not being present when the device crosses is a good mitigation. (If you've done enough bad things they government is targeting you specifically, YMMV)