Emery didn't need to be rushed back to the bank to personally open the safe himself; he could simply have used the CB radio in his own car or the General Lee to tell Daisy and Cooter the vault combination, and then J.D. could have changed the combination afterwards in case anyone else heard it over the CB airwaves.
When roscoe goes to boars nest to get food you can clearly see its in a studio as fake wall with trees and a woman in jacket seen next to studio wall and studio lights.
Luke answers Cooter's CB shout-out by saying, "We got ya, Lost Sheep --- come on back." Luke's and Bo's own CB handles are "Lost Sheep"; Luke would address Cooter as "Crazy Cooter".