Welcome to iRV2.
Sorry your first post is about problems .
The fuse in question , may also provide power to the trailer plug wiring , so checking wiring inside the trailer plug, would probably be a spot to consider .
As with all electrical issues , pinpointing the problem takes 95% of the time .
To save fuses , wire a 12 volt test light across the fuse mount ;with all the bulbs removed ; light on you still have a short , light out you've found it.