Great idea! I was wondering if it might be possible to have multiple adjustments. 

For instance, provide the ability to set each hour of the day or some of the hours of a day so the water rises and falls over the course of the day instead of just raising and lowering at two distinct hours.

You could certainly do this with TimedExecute, calling the command env.oceanlevel X as you wish.  In that case, you wouldn't need Tides.  I'll think about adding something like this, however.

Changed Status from Pending to No Response

Changed Status from No Response to Work in Progress

Changed Fixed In to Next Version

Changed Status from Work in Progress to No Response