My opinion is the only silly questions are the ones not asked.
https://www.lancecamper.com/docs/2005%20Owners%20Manual%20-%20Lance_Lance%20Max.pdflinked is the owners manual to download if you don't have, which may answer some basic questions. Page 27 of the pdf file talks about the 12v.
I assumed physically disconnecting battery cables-note if using a disconnect switch to turn off battery output to camper it also stops ability to charge them.
Once I’m set up at camp, I’ll have the battery connected and the power cord plugged into my generator during the day. I assume this will power all my 120v needs and charge the battery along the way for all 12v needs? Am I correct in that? Yes
Well now I have to go and pull my battery cables...I know our old converter did not supply 12v directly, but responses here make me wonder if replacement does. Just out of curiosity-