The converter fuses would not affect the 120 vac circuits.
If you do not have one, I suggest you buy an outlet tester. Those can give a lot of helpful info and maybe start you on the right path to a solution.
https://www.homedepot.com/p/Power-Ge...212329#overlay
Did you check the voltage at all your other outlets in the trailer? If it is isolated to only that outlet and lights, then I would suspect a poor wiring connection within that circuit. First I would identify the circuit breaker that feeds those devices and check for 120 vac at the circuit breaker. If you have 120 vac at the breaker, but only 60 vac at the outlet then there is a problem within that circuit. And the first thing to look for would be a loose or poor wiring connection. I assume you are measuring the voltage hot to neutral at the outlet. Try measuring the voltage hot to ground. If hot to neutral is 60 volts but hot to ground is 120 volts then you have an open neutral.
If you have 60 vac at the circuit breaker, then the problem is upstream of the circuit breaker panel.
If you have 60 vac at the circuit breaker, then check the voltage at all the other circuit breakers. If you have 60 vac at multiple breakers, and possibly higher voltage at some other breakers, then you likely have an open neutral to the main panel.
This is just a start. If problem is not determined from the above, maybe it will at least give direction on where to go next.