Do you have experience with keeping floating islands year round in the pond?

I created a list of evergreen plants that will tolerate wet feet in hopes they'll work in floating islands or planters in zone 7 western WA state. Our average temperature is around 45 degrees over winter with periods below freezing

My list:
Ajuga, bugleweed
Campanula poscharskyana, Serbian bellflower
Strawberries
Golden Creeping Jenny
Sweet flag, Acorus
Carex, Ice Dance
Armeria, thrift
scotch moss
Rock cress
Ivy, birds' foot or variegated
Vinca minor

When my little garden helper who lives across the road came over last week she saw the kitty litter & asked me if I had a cat now. She was surprised when I said no and told her what I was doing with it. She & her little brother were eager to earn an otter pop by helping rinse 1 1/2 bags of it clean of the dust on the hot day.