Before you do anything you need to figure out how many watts you truly need. With out knowing how many watts you truly need it's hard to help someone.
From what I understand about solar generators it's a battery and an inverter with a high price tag. I forgot there set up for solar to help mess with people. The few that I have read put out very little power.
Why not go with solar on the trailer, upgrade your batteries, and install an inverter. If the system is not sized properly you will end up having to use a generator.