I have heard of people offering food while it was still frozen and have the snake regurgitate later. I have given my big burms rabbits that were still cool in the center and never had the problem. Never tried it with the vipers.
www.SCReptiles.com 2.2 Crotalus adamanteus. 2.2 Crotalus h. atricaudatus. 2.2 Crotalus h. horridus. 1.1 Agkistrodon p. piscivorus. 1.1 Agkistrodon c. contortrix. 1.1 Agkistrodon c. mokasen. 1.1 Agkistrodon c. laticinctus. 1.1 Agkistrodon c. pictigaster. Agkistrodon c. phaeogaster. 1.2 Sistrurus miliarius barbouri. 1.1 Micrurus fulvius. 0.0.1 Micrurus fulvius tenere