Welcome to Air Forums: Your trailer was designed to run off of 12v
. All the lights, fans, furnace, water heater, water pump and the like need 12v
to operate. The 115v AC powers the outlets and the air conditioner. The fridge will also run on 115v AC but won't run without 12v
and propane if the power is disconnected. 115v AC also powers the converter which then powers the 12v system as well as keeps the battery charged up.
Your trailer is designed to use 30 amps of 115v AC power. That is about 3000 watts of power. The AC may draw 1800 watts of that power on a hot day. You really can't run an electric hair dryer or microwave at the same time as the air conditioner.
You also need a good propane system and good propane appliances like the furnace, stove, oven and water heater. It's an old trailer, make sure the appliances are in good operating order. Many times the igniters on these appliances are powered with 12v.
It is certainly possible to run the trailer on 115vAC without a 12v battery. But you need the 12v converter so the 12v systems can work. I might add the battery acts like a "accumulator tank" to help reduce 12v voltage ripple. You can't tow the trailer without a good 12v battery to run the emergency brake system. You would be wise to have both a working converter and battery while using the trailer in a trailer park.
I hope others will provide more information.