I hate to be the bearer of bad news, but you may find this to be a huge struggle! Last year, our twins were 20 months old. Both fought napping with everything they had, and never once napped at the same time. We tried going back to the resort, but all they did was scream there as well! My best advice is to not overschedule and to play the entire situation by ear. You might get lucky, but it's best to go with low expectations!
We are leaving on July 17 for our second trip, and our children are now 2.5. Our plan is to let them nap when they want to in the stroller or wherever they happen to fall asleep! We aren't going to even try to keep our home/daycare schedules and will just go with the flow. Along those lines, if they do not nap, we plan to leave the parks way before the fireworks and return to the condo for an early bed time!
Best wishes!