Is there a battery box on trailer tongue behind the propane cover?
If no......
Inside forward compartment...is there a spot for a battery (two battery cables NOT connected)?
Even a small trailer like yours would have a trailer battery to operate the lights, water pump, furnace, water heater, fridge (12V DC components) etc.
And even a small single axle trailer like yours has electric brakes.
When plugged into 120V AC power (30A for your trailer) the converter would supply the DC System
BUT when NOT connected to a 120V AC power source your trailer battery is what would supply the DC System.
When connected to your Sequoia via the umbilical cord your Sequoia will supply DC Voltage to trailer.........very limited due to size/length of DC Power wire from Sequoia to Skamper
But ONLY when connected.....
Trailer battery is 'required' by FED Law and must be good enough of a battery to provide FULL DC Voltage to trailer electric brakes for min of 15 mins should trailer become disconnected from tow vehicle
If you do NOT have a trailer battery.find where it should be and buy/install one prior to next towing trip