We put a 300 amp-hour 84 pound lithium iron pkosphate battery just in front of the street side wheel well under the sofa of the 23D. It actually weighs less than the two factory installed lead acid batteries. I have about 250 useable amp-hours from this battery.
There are five 100 watt solar panels on the roof that could charge at around a 375 watts charge rate on a bright day into the BlueSky 3025iL charge controller. The Magnum MSH 3012 converter inverter is on the other side of the furnace and under the dinette seat on the same side. No external modifications were necessary to the Airstream cabinetry.
We put a 600 amp-hour lithium iron phosphate battery at 168 pounds under the front sofa on our Classic along side a Magnum MS 3012 charger inverter. We have eight 100 watt panels on the roof that have generated a 575 watt charge rate on a good day.
The common location choice was to get the battery weight closer to the trailer wheels and away from the tongue.
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC
TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell
2014 31' Classic w/ twin beds, 50 amp service, 1000 watt solar system, Centramatics, Tuson TPMS, 12" disc brakes, 16" tires & wheels