Nancy the cord, not a bad idea on the LED's, would only help you if you remember to look at the indicators and immediately unplug if they show an error. If I am reading the literature correctly if you leave it plugged in bad things like fires may occur.
The TRC will not even allow current to flow through the TRC box if it finds a ground fault. It also does other things like surge protection. I used a built in TRC on my FC25 but went to an external 50amp Progressive EMS-50PTC for my Classic. The warranty if ever needed is better on the Progressive. Pricing from Amazon makes them comparable to TRC.
No issue on using both the Faultsmart and a surge/fault unit but not much gain either since the surge/fault unit does it automatically.
Personal bottom line, get a surge/fault unit.
2015 GMC Sierra 2500HD Duramax