The difficulty with our little fiberglass trailers is everyone wires them up a little differently, so anything we have to say about it is going to be a guess.
Looking at your panel, it appears you have one 30-Amp breaker and 4 15-Amp breakers. Neither your converter, nor any other 120v appliance in your trailer draws that much power, so I will venture the guess that that breaker is for your main hookup line. You have to turn it on to get anything else to work.
That leaves the other four 15-Amp breakers. My guess is they are for:
1) Your converter
2) For your AC (or a pre-wire job for an air conditioner)
3) Your refrigerator
(perhaps also a microwave
4) Your trailer's 120V plugs (and perhaps for a microwave
Here's how you figure out which is which:
1) Get yourself 3 120v lamps you can plug in. Or a microwave
with a clock display. Or a clock radio. Three things you can see or hear when they have power.
2) Find the following plugs and plug one in at the plug in for your refrigerator
(you can find it by following its power cord), the plug at the back of a cabinet where your microwave would sit. (Or just plug your the microwave in.)
3) One of your accessible 120V plugs, like the one where you might plug in a coffee maker.
4) Disconnect your battery, turn all of your "test" devices on, turn on one of your 12v lights
, then turn all of the breakers on. Do not turn on your air conditioner (if you have one.) All your "test" devices should come on when you flip the 30 Amp breaker.
Now flip one breaker at a time to the "off" position and see which of your test devices goes off. The one that does nothing is for your A/C.