I ran 12AWG about 195' from the circuit breaker box to the TT. With just the Air Conditioner running and D.C. Converter, voltage was 103.7. 112.5 at the TT inlet without the AC on. At house, voltage was 125vac. Forget 12AWG supplying several TT items at the same time.
Parked at another place at home, 90' of 12AWG with AC & converter only, voltage dropped to 107.7.
All measured using a Kill-a-watt meter.
In your case, go with 6awg if you can afford it. 8awg minimum. Actually, strongly consider a closer storage site to the power source. Less voltage drop, shorter length of wire making thicker gauges more affordable.