I installed TWO Full River 6 volt (220 amp) almost a year ago in my Axis and I absolutely love them. So much easier than LA plus they charge quicker and discharge much slower than LA.
They are more pricy being AGM but IMO they are worth it. I purchased from either Battery Depot or Battery Outfitters locally. And when I picked them up I asked for a discount and they gave me 10% off so that made me happy.
One of the main reason I went with Full River was their AGM 6 volts fit under my steps (some other brands would not) with zero mods so that was very important to me. Plus I was able to pick them up locally (and return myself them if I was disappointed).
They are heavy (73# each vs 46# for my OEM batteries) but I was able to install by myself.
I might someday add a couple of more (perhaps if we boondock for a weeks at a time and add solar) but I have limit storage so I hate to take up the compartment next to steps at this point.
Plus these two AGM's give me more than enough reserve power for weekend camping and all day picknicking so currently I dont see any need to add more.
2017 Axis / 25.4: Big Foot Levelers, Aims 1200 Watt inverter, Ceramic Window Tint, Full River AGM 6V batteries, Front Hellwig Sway bar / Rear Track Arm, Safe T Plus Steering Stabilizer, PD 4655 converter, Hard Wired Surge Guard, WEboost + WiFi Ranger, LED Headlights/Driving lights, Fresh water surge tank, Black Tank Tornado flush, 4999 zip ties.