Hey there.
Last summer I took my MCAT on June 20th and had the score release sometime around July 25th (38 which I could not have gotten any other way than with the extra month of studying) . I applied to 18 schools, had 7 interviews and am accepted at 4 (UVa, Ohio State, VCU, EVMS) and waitlisted at another 3 (Duke, Northwestern, Case). My GPA was 3.83. It is definitely possible to take a late MCAT and have a successful cycle.
I think a summer MCAT is absolutely possible but to echo others in this thread you need to take the MCAT when you are READY. This is incredibly important and I cannot stress it enough. At this point you have already swallowed the bullet (correctly so, I might add) in that you have resisted peer pressure from your friends to take the MCAT during April or May.
I have seen so many people screw over their entire application with a subpar MCAT score since they attempted to balance a full schedule with MCAT studying at the same time. Some can do it, the vast majority (myself included), cannot.
Good luck and PM me if you want further information.