Also, here is link to the Victron solar charge controller (SCC) Manual. If you didn't receive one with the trailer you can download it here.
https://www.victronenergy.com/solar-...pt7510#manuals
Section 4.5 Electrical Connections, provides information on connections and the order to make the connections. In your case, you should have a switch on at least the positive conductor between the panels and the SCC. You may have difficulty finding a suitable switch rated for the necessary DC voltage in which case you can find a breaker to use instead. The voltage in this instance is the voltage from the panels and can be up to 100 volts for your SCC. In my case I have 2 x 210 watt panels connected in series. My total Voc is 80 volts so I can use the same SCC you are using.
The reason Victron wants the SCC connected to the battery before connecting the panels is so the SCC can sense the battery voltage before the panels are connected. The SCC you are using can output 12V, 24V, or 48V depending on the battery.
When you disconnect the battery, you will want to switch the panels off and only switch them back on after you reconnect the battery.