When you remove the old wiring, do it one piece at a time and replace each wire with a new piece that is at least as heavy as the one you remove. Make sure to include all fuses. If you are replacing the light
fixtures, receptacles, fan etc. do it when you replace the wires.
Calculate your amp/hour power usage and buy solar
panels with twice that amount to account for low sunlight conditions during cloudy days. Mount your solar
panels on the roof or mount a bracket that will hold them if you plan on removing then during travel or when your unit is in storage to keep them in good shape.
Wire your solar panels into the leads connecting your RV battery
to your trailer. That way your solar panels feed your battery
and the battery
feeds your trailer. Make sure your RV battery has twice the capacity your trailer needs per night to prolong its life.