Your lights and slide outs are run on 12V power, so is your propane detector and some other things. A good way to test whether you need one or not is to unhook your battery the next time you're at a full hook up park and see what stops working. Then decide if you want to eliminate the battery. My guess is you'll want a battery.
2020 Silverado 2500HD LT, CC, 4X4 6.6 Duramax
2021 Grand Design Reflection 311BHS
I asked him to do one thing and he didn't do any of them.