I'm as libertarian free-rights paranoid as the next slashdotter (while not quite), but a healthy dose of history here. Customs, border crossings, etc. have never had anything to do with democratic values
Completely incorrect. Many of the British actions to diminish liberty in the 1700s were directly related to enforcing customs and duties: writs of assistance, vice-admiralty courts, etc. The Founding Fathers were reacting in part against British regulation of customs and duties so many of the "democratic values" like the 4th Amendment, the requirement that trials be held in the locality where the crime was committed, etc, were in fact developed in response to customs enforcement.
The most poignant example is writs of assistance. These were open-ended search warrants that authorized the holder to conduct any search whatsoever and were issued to British customs officers in the colonies to catch smugglers. They outraged the colonists, who saw them as an affront to their liberty, and directly led to the requirement for specific search warrants in the early state constitutions and later in the 4th Amendment.
I find it most ironic that the restrictions on search warrants came in response to arbitrary customs enforcement by British customs officers, but today no restrictions at all apply to searches by American customs officers. Whatever court ruled that the 4th Amendment doesn't apply to border crossings ignored significant precedence to the contrary.
See Writ of Assistance in Wikipedia for a pretty decent overview.