Does anyone have any advice on the lowest-cost (to avoid customs duties) method to mail some boxes of used, personal clothes home to the USA from France (winter clothes we brought that we no longer need)?
Rick mentions in his guidebook that you can mark a package (and/or a customs form) "American Goods Returned To USA" and "slow boat" it to the USA (I don't know exactly what he means by using the slang "slow boat"). I am guessing the purpose of indicating "American goods returned" is so you avoid paying USA import duties on clothes you had actually bought back home in the USA.
Unfortunately, Rick does not elaborate on mailing things home in his guidebook... just kind of quickly mentions that you can do this without providing much detail (probably because he's hoping that, as a traveler, you never brought more clothes than needed!).
As most people know, mailing anything from Europe to the USA is ridiculously expensive (and probably vice-versa). So any help is appreciated.