I'm not sure that I fully understand your question, but let me define a few terms.
verter uses 110 volt AC power to create 12 volts DC to run 12 volt accessories and to charge your battery
verter uses 12 volts DC from the battery
to create 110 volts AC.
Most people have a converter to power their trailers while AC electricity is available and use the 12 volt battery
when AC power is not available. A solar panel
will directly charge the battery and make it last longer while no AC power is available.
You can use an inverter to power 110 volt small appliances from the battery, but unless the appliance takes little power, or is run for a very short period, the battery is quickly depleted.
What devices would you want to power in the trailer?