Another thing you may want to consider for some of the shoots - shoot a portion of the images from a stool or short ladder.
By slightly elevating yourself relative the position of the subjects, you will be visually "lowering" the horizon and level of the lake in your frame. The subjects still get the lake background they desire, but the bright sunny horizon line can be decreased and even eliminated. It's all about viewpoint. And just by having the texture of only the water, this simplifies the background and brings more attention to the individuals.
I've done a few water related shoots and this technique is very effective. It's not a perfect solution, but handled properly you will deliver a different sort of pleasing look that your competition may not use. You have just set yourself apart from the other GWC .