OK, you have a short, now lets find it. You probably have only (2) 120v circuits, the AC, and the Cabin, but if you have more, fine.
You will need a battery operated continuity tester.
(1) Disconnect power from the house.
(2) Go to your trailer Circuit Breaker box.
(3) Test continuity between a BLACK wire on a Circuit Breaker and any WHITE wire.
(Do not go to GROUND because on a trailer the WHITE and Ground are separate)
(4) If you get a reading, that is the bad circuit, and you just have to follow the wire
to find it. Double check yourself by switching off the Circuit Breaker, and connect the house connection. If the house Circuit breaker does NOT trip, then you are sure you have the right circuit.
Hope this helps.