The main reason Academies don't allow contact lenses during the plebe summer is due to hygeine regions. There simply isn't time in the day to properly care for contact lens use, especially if you go to the field.
Some would argue that those who wear extended wear lenses wouldn't have this problem, but you really probably shouldn't even wear extended wear lenses overnight as it increases your risk of infection from somewhere in the range of 1 in 10,000 to something like 1 in 5,000. An infection is definately not something you want to deal with during plebe summer, so just go with the BCG's for the summer.