From what I've read,
since it appears that your Anderson connection goes dead when your ignition is off, you don't have to worry about draining your car starter battery.
since you charge your AGM battery at home, you don't have to worry about your AGM battery unless you run it dry.
Me, I run two vehicles and two trailers for a few hours each week and I've been looking into how to keep the unused tow vehicle battery charged up without having access to a 110 volt line during the week... And also the battery of the tow vehicle that gets most of the use since it doesn't always get a full charge from being run a few miles every weekend and then sitting for most of the week.
My current solution has been to charge two batteries in parallel in the toy hauler Trailer (it gets hooked into a 50A 220 line split) and then charge the little trailer and the Yukon, by running a 110 line from The toy hauler Trailer, and alternating weeks between the little trailer and the Yukon battery.
At one point I had to replace all four batteries before I came up with the idea that I shouldn't ignore the batteries.
I used to run an extension off of the toy hauler battery to charge the second battery, but from what I've read it's better if I put One charging lead on the toy hauler battery and the other charging lead on the second battery. It's about leveling out the resistances which means that each battery gets a good charge without being over taxed because of the resistance and balance, or some such.
So basically I've got the charger positive lead going to One battery, and the charger negative lead going to the second battery, or the end battery in the chain if I have more than two batteries.
And of course I should be using the same gauge wire all around, which I think is 8 gauge but the 8 gauge is a pain in the butt for me to deal with unless I run clamp screws or wire nuts.
And of course both tow vehicles use side mount terminals on their batteries which I really learned to hate, so I've got auxiliary battery posts that I can use with a quick release battery clamp for the auxiliary charging battery.
The toy hauler is actually converted to run 7 dryers and washers for homeless people at a local church on Saturdays.
The small trailer is from a movie set and it's a shower trailer.
When the on-demand heater got replaced, someone thought it was a great idea to put in a 110 volt on demand heater instead of replacing it with a 12 volt on demand heater running propane, so now we always have to have 110 volt to run the showers heater and enough water pressure to get water out of the shower heads.
We used to be able to run the shower trailer without any 110 line voltage at all for one day or about 8 showers out of a 100 gallon tank, or 16 showers before our gray water tanks get full.
Serves me right for letting someone else handle the on-demand water heater replacement.
The room lights only go off in the main power shut off.
So of course during covid when the water heater got replaced, someone forgot to turn off the main power, and then ran the 12 volt water pump, and ran the 12 volt battery dry, which meant that the water pump ran off of the charging system, which burnt it out, which meant no more lights but at least we had hot water.
Until I figured out what happened.
Which is why I run a separate battery charger to charge the small trailer, instead of the built-in battery charger and no charging if the pump is running.
If course the small trailer (and the toy hauler battery) battery is a pain to unhook and drag out (I'm not skinny enough) or I'd just pull it out and drag it somewhere I can plug in a charger when the trailer isn't in use.
We've had one or two people come out to look at the trailers, but don't ever comes back to fix the 12 volt system by replacing the onboard charger, since it's a low priority.
I probably should run a relay to the lights, so that they get shut off if the main power switch is left on, but I don't want to run a sensor to the 110 volt line, and I'm not sure I trust timers.
Maybe I'll throw an LED light on top of the main power switch to remind the operator at the power is still on, because it's hard to see the room lights once you button everything up and the Sun is up.