This solution is too complex. Each waterside lot in a POT is placed by it's governor for any waterside home - not just for watermill homes. And the bodies of water ingame differ ranging from rivers to lakes to seashore biomes. To rotate the house, the lot itself has to be rotated by the governor and this is everytime the lot owner changes his mind (maybe even changing his house). Just visit Kingsport which has 3-5 lighthouses on both sides of the river in what is a very short stretch and you'll what the potential amount of work is involved. No governor will be willing to do it for long. The simplest fix is to relocate the wheel to the back of the house so at least the wheel is aligned with the river. Having to the wheel rotate in the right direction is another matter.