Generally speaking for me, if I can keep my battery voltage above 12.6, I'm happy and this 12.6 number is the typical full charge level for 12 volt automotive styles of batteries. My solar panel charge controller screen has a voltmeter which makes seeing this voltage level easy but any inexpensive Harbor Freight multimeter would be OK to use.
The main battery will eventually drop down to 12.1 or so by morning before my panels start putting some power back in. You don't want to let a lead-acid twelve volt battery become overly deep discharged too many times because this will damage the plates inside the battery case - time for a new battery. If the main trailer battery starts to get much lower than 12.0 volts, I will kick on the Jackery Explorer 500 power center battery to supplement the main RV battery and prevent damaging it. Then the panels recharge both the next day.
Rick