Big beans are zoned 5 to 11. I don't have either the Bogbean or water clover, but my plant book says Bogbean slow to establish in the water garden, requiring even 2 to 3 years before lush growth is attained. it also says addition of acid to the soil, in the form of peat, enhances plant performance. Does not say how to winter, but if your in zone 6, you should be just fine leaving it in the pond to winter, seeing how it takes 2 to 3 years to establish, don't be moving it around.
The water clover is zoned 6 to 11, highly invasive, may need to be monitored as this plant can choke out other plants. Just leave some of the rhizomes in the pond, plant may need to be "thined out" weekly my book says.