We did this with Disney in 2011. Did Disney tell you that the Rhino could take 3? For us, in 2011, this wasn't an option. We thought we could do that, or that one of us would ride alone. Once we arrived, the Rhino Rider company told us that one person could pay double to ride by alone, or the other person had to ride with a guide
...we wished we had known that. Yes, our other child was 11, but they wouldn't let 3 on a Rhino Rider at that time. So we paid for 5 individuals (I think $88 a person?) and for one of us to ride with a guide.
Once you get there, there is a speech about what happens, a chance to change and buy stuff in the shop, and then a talk about tipping afterward. They also push a picture (for a fee of course) as you take off.
You follow their guides (yes, pretty fast) and are not allowed to go off on your own (just in case your thinking it's a free-as-you-go experience), and they take you to a little lagoon. It's a small beach where you can explore, snorkel or just relax. We weren't there very long (thinking 30-45 minutes). They did offer water at some point, and then we headed back.
At that point, they are really hovering and pushing the tipping. We understood that, but
talk about pressure! And just so you know, there are only 2 bathrooms, so if you want to freshen up or get dressed, it can take awhile for everyone to do so.
Would we do it again? Nope. It was fun, but once was enough.