So, my first question is......when you plug into your outdoor outlet, is it a GFI plug? If so, you are probably tripping the outlet as soon as you plug in. That was hwat was happening to us. So here's what you do (according to my cousin the electrician).
1. Turn off the main breaker. You don't want ANYTHING drawing power in the trailer.
2. Make sure the battery is disconnected.
3. Plug into your outdoor outlet.
4. Flip the breakers in the trailer and everything should be powered up just tickety-boo!
5. If this doesn't work, remember that it was my cousin who suggested this. I'm just the messenger.