Peter thanks for posting the setup and pictures. Neatly done.
One thing I would mention. I think the PWM controller might put spikes and garbage on the power rail. This will not cause any problems to the dew heaters
but may cause damage to more sensitive electronics using the same power supply. I'm not sure what Nexus is
My own system uses one supply for the dew heater and a separate supply for the Mount Electronics/Hand Controller.
Someone more knowledgeable than me
might chime in or you may already be aware of the possibility.
Michael