If it were me, I would just leave the OWB on all the time and let it heat the hot water. Add wood at night to get it up to temp. , and let the fire smolder all day.
Also, out here in the wild west, we cannot have fires or smoke in summer. Fire restrictions. We also have a solar hot water system that I tied the OWB into, and it works fine from now through about October. Simple really. I designed and plumbed a convection loop in the electric hot water heater with a heat exchanger at the base that is connected to the OWB loop. The solar hot water heater has its own pre-heating tank, and that feeds the input to the electric water heater. Standard installation around here. You can turn the electric heater on if you want, or use it as a second storage tank, which is what we do. This time of year we get double heating; solar pre-heat to about 100 deg, and boiler final heating to about 140 deg. It is really quite easy to plumb. If we did not have the electric secondary water heater, I would have plumbed the OWB heat exchanger convection loop directly into the solar water tank. No difference, really. Our solar tank is an antifreeze type solution that runs to and from the panels, and there is a coil in the tank that heats the water. This system was already plumbed though, so I close the electric tank to plumb the OWB Hx convection loop onto.