Yes, impossible to find your board when it sits "in" the water surface, and as there is usally a bit of small chop it gets out of sight, and colours dont work if a flat board
I use a Rubber Duck - a hole in the bottom, a big washer or similar inside the duck, and then a screw through the deck with a washer/nut on the bottom
On a normal board, I would simply use a countersunk screw in a small plastic plate or painted/laquered plywood and stick it to the nose of the board with dual adhesive or contact cement (can be removed easily later)
When you stick it like this, it can take some abuse when you hit it in crashes - which it would not if you try to glue or tape it - wont work...
It has to stick quite well even for a normal start, the board sinks deep
10-4 RubberDuck Hero6 on a stick
I have bought a bigger duck too, but havent used it yet as it works fine with the duckling above
You learn to know where it is though, as said, so dont really need a big duck.