Any reason this wouldn't work?
Redirect hose from thermostat to the heater and run the return back to the water pump.
I 'll add shut offs to bypass the heater in the summer and run the coolant from the thermostat directly back to the water pump.
The inside diameter of the rad hose is 1 1/8 inches so I need a barbed T from 1 1/8 rad hose to 5/8 inch for the heater hose.
Any idea on where I might get it?
There is a problem with these as they go open after a very short time.
Maybe the water drops below the heater a little and they burn out.
You might want to check yours if it's older than two years.
Time for an oil immersion heater.