My daughter hates sleep too, but I've slowly been getting her to take longer naps, and it's been so helpful for me (and her too). She used to do 1, maybe 2, naps a day, about 45 minutes each at the longest. Now sometimes they'll be as long as an hour each. The only good thing though was that since she sleeps in our bed, I'd lay down with her at naptime until she'd fall asleep and sometimes I'd end up napping with her. Of course, I never got anything done, but when you're on vacation it doesn't matter. So try to nap with your son in WDW during the 3 hours he does nap. I really needed it when I was on vacation while pregnant (at 6, 20 and 28 weeks). Some time in the pool will be relaxing, but I found that even on the days that I was in the pool, I still needed a nap.
I too went on the safari ride at 20 weeks, 3 times, but if you go, ask for the front row, even if you have to wait for it, cause it's much less bumpy. I still asked for the front row when my daughter rode with us at almost 3 and almost 4 months, and she loved the ride too-like riding in a car without being in that restraining carseat!
By the way, people always tell me my daughter doesn't sleep enough (less than 2 hours napping and about 6 hours at night) and to put her to bed earlier. Well I tried that, but then she woke up after 45 minutes like it was a nap and was then up forever, or she'd wake in the middle of the night thinking it was time to be up for the day and play. So we too have accepted the fact that she'll never be a sleeper.
