I would love to see how the water would look like if you indeed could freeze it :p I don't think it will work though. The water boss wasn't that hard to defeat but he isn't that stupid I hope :P :lol:
You don't necessarily need Epona to cross the gap. You can use the longshot. I finished OoT without getting Epona (of course I skipped the Biggoron sword quest because there you need Epona) and at Gerudo I simply used the longshot to cross the Bridge. But this means you must have been at the...