To comply with §2257 you will need to provide the buyer with a government issued ID of all the models featured in the depiction as explicit is defined by §2256
https://www.law.cornell.edu/cfr/text/28/part-75
The model's name, picture and ID issued number must appear on the ID document the model's address can be redacted (blacked out) -- the ID would need to be furnished to the buyer -- for the buyer's records. Maybe, Ma Dalton will reply to this post he is in CZ and sells §2257 content in the US.
Commercial copyright license documents are not within the §2257 requirements but they would be needed in a content sale.
Not legal advice -- for comment only