My partner and I are looking to have a natural heating source for cooking and heating water for a bathtub that will go in our Skoolie. We will be completely off-grid using solar, and heating that much water with solar and an on-demand water heater would completely drain our batteries. We were looking to get a wood stove before I discovered rocket stoves, and now knowing these are more efficient we want to work one into our build. We'd like to have a cooktop on top of the combustion chamber, and then have the exhaust pipes go underneath or around the bathtub to help heat the water. We're thinking that maybe this will not be enough heat as far as the exhaust heating the bathtub, so we are thinking of putting copper coil inside the chamber that will circulate water in the tub as it heats and rises. Any thoughts? Our bathroom and kitchen are next to each other, so the cooktop and bathtub will only need to be separated by a very thin wall or even a curtain if necessary.