I am sure that this solution would make the US government very happy, but unfortunately there is one small flaw (apart from the difficulty of getting such a bill passed in Congress). The National Debt is not entirely owed to foreigners, but much of it to US citizens instead, who would presumably be quite annoyed by such a ploy as would those retailers who ended up with the worthless paper money. In addition, where would these retailers obtain the money with which to buy back these material goods?
A very similar tactic has, however, been used in the past, most notably by the French Directory in 1794, who printed a paper currency backed by land appropriated from the Church. The assignat, as this currency was known, was then used to pay off governemntal debts but within two years had crashed to 0.3% of its face value.