The hot water on my boat comes out scalding hot.

My water heater is always on when I'm plugged into shore power (unless I hit the press button breaker on the panel to disconnect it.) This means I can only use so many electric heaters to warm the cabin before it trips the outlet breaker. 

I am wondering if anyone has used a hydronic heater, powered by the 6 gallon Seaward water heater, to heat the cabin while at the dock. There was a Tech Article on the C34 site about using one while underway, which supplies hot water from the engine coolant/heat exchanger/water heater loop, which outputs a constant temp of 160 from the engine: https://c34.org/wiki/index.php?title=Cabin_Heater

But I'm wondering if I can just use the water heater alone, while plugged into shore power, with the engine off and make more use of the electricity that the water heater is drawing anyway. I've seen the HeaterCraft 500 here: https://innerdemonmotorsports.com/products/500-grill-face-series-heater

My thought would be to hook it to the hot water heater out line, with a return line to the water heater in. I think I would also need to put a recirculating pump on this loop, wired into the same switch the heater would be on, to circulate the hot water. The bonus would be it should also work while underway, since the engine heats the hot water heater anyway. 

But I don't know if the Seaward water heater would be able to keep up enough to produce warm, consistent heat while just on electric. Has anyone tried this, just using the water heater to produce cabin heat while plugged in at the dock?