John F that is what I decided about what I call my "pre-sediment" pond. It was a tiny pond right ahead of my sediment pond that I tried also raising FHM. But I came to the same conclusions as you have and connected it to my sediment pond.
I wanted to be able to drive my 4 wheeler between them so did not want just a ditch between the ponds to connect them. So what I did was bury a 6" pipe between them then made the area between them rock and gravel just barely above water level. Then during minor rains the water just flows through the pipe but during any larger rains the water flows both through the pipe and between the ponds over the rock area.
You likely do not need that feature but that was my solution to both have the ponds together as one yet still be able to drive where I wanted to.
