I'm open to suggestions.
What if you had the BTC seller send the BTC to the trusted escrow, and then also ship the box of cash to the escrow, and then the escrow can forward the box of cash to the BTC seller after the escrow confirms that the box does indeed contain cash of the proper amount.
$1,000 does not require a box, but point taken. I suppose that would work despite the extra time and shipping costs and extra work for the escrow provider. I'm open to it if someone really wants to do it that way and pay the fees.