If you and your RV can handle the weight of the two GPL-L16T, that appears to be a rather elegant solution. With an average usage of 70ah/day, you would be bumping up to three days without any sun before enlisting shore power, solar harvesting, or a generator to keep to a 50% discharge rate.
When configuring two banks, the exercise gets more complex--more wiring, switching between banks, monitoring both, etc. It's unlikely that any existing DC wiring from the engine compartment to the distribution center will be large enough to adequately handle typical charging or discharge.
