Sorry - that just doesn't sound like a workable solution to me - changing a tank from FW to marine is time consuming (you need to start up a marine biofilter) and then, once you have the ich under control, you'll need to remove the copper from the tank, and then, the anemones can still carry active ich back to the tank as long as 75 days later. The Kenya Tree and Xenia (and any other invertebrates) would also have to be moved.
At this point, I think you should either try the Ruby Reef Rally, or just hope for the best and see if perhaps this isn't ich after all, and the fish can recover. Sometimes, there just simply isn't a good cure, given the existing circumstances.
Jay