Oka, sound slike a good start at a good plan to keep the batteries charged. AGM are absorbed glass mat batteries. they are a nice step up from the older lead acid as they need less watch on water and such, but still can be a problem as we learn what to expect.
You are likely to find that there will be some small drains left on both the coach and the chassis batteries.
Yes, a small trickle charger can be a big help BUT it takes some thought to make sure the charge is getting to both sets!
I see the chassis batteries seem to be in a panel just behind the driver. But I don't see the coach batteries and not sure how the best way to get the positive of both tied together? Some RV have both sets in a panel under the steps but that doesn't seem to fit what you have. Since both sets have the negative tied to the frame as ground, if we connect the positives together at some easy point, we can use one trickle charger to keep all the batteries charged!
If we have both sets of batteries charged when we pull in to store, the current need to keep both charged is very low, so we can use small simple wires instead of the huge bulky cables we use for jump starting things!
I use a stranded number 12 wire with alligator clips on both ends to tie them together and only use one charger. Others find two chargers works for them.
Just to be alert to not let either set run down so low it damages them.
Stay alert, keep them alive, may fit?
I'm an old fan of Moose Lake and North of Ely! Those were the days! Long ago when I had no more fun than living in a half frozen ice box!
Is that why my knees hurt so much every time it gets down to 50? Maybe they've forgotten what real cold feels like? AARGH!