That solar charger is rated 1.5 watt. Thats 1.5 watt in bright sunshine.
assuming its nice weather and you get 8 hours direct sunshine then thats 12 watt hours a day, to be realistic though in the winter you could cut that by a factor of 4 or more.
a typical bilge pump will draw say 5-10 amps lets say 5A thats 60 watts.
if it runs for 1 hour, then thats 60 watt hours.
so thats 5 days to make up for 1 hour pump running in the summer and 20 days in the winter!
However a fully charged 130AH leisure battery would run the bilge pump for approx 26 hours anyway.
I like the wave powered option if it works! however i think a second battery and an electric pump in conjuction with a well fitted cover is the best way to go!
I am usually not as green as i am cabbage looking.