Hi there-- I too had a very early riser (5/5:30pm) and had to revert to a very early bedtime when ds was 18 months old. He was going to bed at 6:30 , waking 5:30am and crashed and burned around 10/10:30am most days...as I work full time, it was hard to keep him on a schedule because he would often fall asleep in the babysitter's car. ANd he was only sleeping about 1.5 hours for his nap.
At about 22 months, he started waking up a little later and we gradually started putting him to bed @ 6:45-7:15pm.
This past summer(he was 2.5 years old), he was able to stay awake until 8/8:30, even 9pm on weekend nights and took a good 2-3 hour nap and woke 6:30-7pm most mornings and he would not crash and burn in the car in the early morning so I do think that you will definitely have less restrictions next summer...
ANyways, just our experiences with a sleep sensitive child!