My neighbor mentioned buying a fairly long piece of HVAC duct, fitting it over the spinner of a deer feeder and directing the other end over the water 8 or 10 feet. That seems like a cheap way to make sure all the feed gets into the water. It may not look pretty but it ought to work. Otherwise you could drive a 4x4 piling into the lake bed and fashion a method to attach a deer feeder to it then refill from a boat.
