When doing both parks what is the best way to manage changing? Do people do the theme park first, then change and go to the water park or vise versa?

They have place you can change but might want to wear it under the clothes that way you can be ready and not be in line.

There are plenty of places to change in both parks. Id wear my suit under my clothes because there are some wet rides in the funtown side.

I recommend going when they first open at 10 and going to the water park there isn't a lot of people there so you don't have to wait in Crazy lines you'll notice after around 2 hours or so you get bored of it there isn't that many rides after all the best thing to do is change just leave your clothes like with your cooler or whatever else you brought at Splashtown in your chair that you had and then go to Funtown and when you're about to leave make sure you just run back to Splashtown and grab them it's what we did last time and it was super easy and fun

Yes it js

Funtown is open later than Splashtown.