I would suggest:
1. Set your location flag to USA
2. Start a topic for the clearout, to list what you are offering, with a photo of each proposed box, one post per box, and another for all questions and bids.
3. Ask bidders NOT to PM you or post in your listing topic.
4. A bid may be an offer of payment or 100 words to encourage you to donate a box.
5. Anyone who wants other than continental USA flat rate box shipping must pay for courier collection to be scheduled at your convenience.
6. Close bids on any box 24H after the first bid on it, flagging the original listing post as 'Sold', and making a "Sold/Donated to ...." post in the bids topic.
7. Blacklist anyone who cant/wont comply with your simple rules
As I'm not continental USA, I don't have any skin in the game but IMHO this two topic open bid system will be both interesting and fair, but still easy for those who aren't interested to ignore. You might as well use this topic for bids/Q&A.