Do you dry camp a lot or it's just for brakes and the occasional stop? I used to put Optima's in everything, however, I never got more "life" out of their batteries (Coincidentally, they are owned by Johnson Controls, who is my parent company)?
I used to run 2 batteries as well, never really needed both as when we dry camp I use my Honda EU2000i to keep my batteries "topped off" and to operate microwave/TV etc... and using Deka's over the past 4-5 years have served me well in my campers.
I personally wouldn't spend high dollars on an AGM if you tow from point A to point B and it stays plugged in to shore power...just my $.02.