When we took our first son to WDW he was just 7 mo old and was also an "only in his own crib" napper and a light sleeper. Prior to the trip, I spent a great deal of time worrying about how he would be able to nap in the parks (I worried about him sleeping in the hotel room at nights too). I pictured me dealing with a sleep deprived, miserable baby throughout the vacation. Once we were there I found that, as usual, all my worrying was for nothing. He actually slept MORE in WDW than he did at home! I guess it was all the stimulation- all those sights and sounds- combined with the fresh air. I found that he would fall asleep in the stroller (we reclined it when we knew he was sleepy) while we walked around, between attractions. Once he was out, instead of yanking him out to go on a ride, I would continue to wheel him around and do gift shops and enjoy parts of WDW that would not require me to take him out of the stroller. At home, he was the kind of baby that would wake to noises but in WDW he was ZONKED and would sleep through things that surprised me! Also, WDW is very stroller friendly. I distinctly remember that DS 7 mo. fell asleep just as it was time for our dinner reservations at Alfredo's. Well, I asked, and they said to bring the stroller right in! They took away on chair at our table and we wheeled the stroller under there. DS slept through the entire dinner and DH and I had a very enjoyable meal! He woke refreshed and happy just as we were done eating!
For our following trip, DS #2 was 12 mo. old and we found the same to be true for him, regarding his naps.