I suppose making a safety case is a realistic option.
Taking into consideration that the EASA rules are written with the intent to increase and guarantee public safety, and should be followed in spirit more than to the letter, the fact that the passengers of these historical aircraft are well aware that it does not meet modern safety standards much like the classic cars that are driven and sometimes raced by enthusiasts, the very limited exposure time per passenger and the usually very benign weather they operate in, one would think that somehow an exemption for this type of operation should be possible.
I know I am assuming some common sense in organisations that are not famous for displaying it, but still..