I'm happy to report success with my battery quest. First, I was delighted to find that my setup was indeed balanced, and very nicely done (by myself, so long ago I don't remember doing it lol)
Second, I found at AutoZone a "true" 12 volt deep-cycle. Duralast also makes a "combination" battery and that is what I was replacing. It was not an easy item to find as only one out of 6 "local" AutoZones stocked it. It is not a Trojan but for the price it may be worth it.
I got 5 years from my old "combination" batteries and did a lot of dry camping during this time. I is hard to imagine doing better than this but I guess we will see.