I have 200 watts of factory solar installation and I've seen 11 or 12 amps occasionally on cool windy days with high sun angle. Winter I may see 6 or 7 amps peak on a crystal clear day. I'm sure my wiring is less adequate than on a good custom installation.
Every bit helps and I perfectly accept I may park the RV with a battery deficit. It charges later while parked.
My two suggestions: get as much up there as you can. Even if you can't get 200 watts, shoot for 140, 160, try to squeeze in a bit of extra. Good for part shade, winter, etc.
I just don't get the two battery in sequence thing. Personally I'd tie them together and forget it. You may benefit a bit by the Peukert effect. If you have an emergency and have to dip into less than 50% state of charge-so be it. Once in a while it won't kill the batteries. You have tow vehicle battery/alternator for worst emergencies w/ jumper cables.
