Jim Andrada

"As the National Guaranteeing Association, USCIB is required to take security, usually 40% of shipment value, to cover any customs claim that might result from a misused Carnet. Acceptable forms of security are certified check or surety bond. Cash deposits are returned in full and surety bonds are terminated upon Carnet cancellation."

Seems pretty clear that it's indeed 40% of the value of the equipment. If I were you I'd certainly look into the surety bond option.

I've never gotten one myself but have received goods that came into the US on a carnet. It was actually sort of a hassle dealing with the specifics of how to use it and how to return the goods, but I think this was because they were shipped by air freight and getting the paperwork from the customs brokers/shipping companies was sort of complicated as they have very specific and arcane policies about to whom they will release the paperwork and the physical carnet itself. As an "amateur" importer/exporter it was pretty confusing

I think if you're "hand carrying" the equipment life will be simpler as you'll be the original carnet holder.

In any case, give the USCIB folks a call and explain what you're trying to do and ask their advice. People tell me that they're easy to deal with.