I've thought of this problem myself. I dont see why you couldnt buy a really small hot water heater, maybe something out af a science lab catalogue, (it would have to take the water pressure) 110 volt. then install it on your hot water line under the sink. That wouldnt be major plumbing. Youl'd have imidiate hot water and when it starts to run out the regular hot water would kick in. It's probably against code, but I cant imagine why. Maybe they make units exactly for that purpous. Or maybe nobodies invented it yet...Here's yer chance.