The Parallax converter is single-stage and not suited for quick charging off a generator. And the 6A charger is woefully inadequate for even a single 12V battery. 70W of solar will help but it won't supply all your power needs.
If you're serious about being off the grid for 2 weeks at a time and plan on keeping the trailer a while I'd consider upgrading the converter to a PD, IOTA, or maybe a Boondocker from Bestconverters. Second choice would be to buy a 40A (minimum) battery charger.
I installed an IOTA 55A deck-mount converter, mounting it to the ceiling of the front pass-through. It's a 3' wire run to the batteries and the factory WFCO converter is only used as a DC power distribution center. I run the genny an hour a day and my batteries are typically at 12.3V before I start a charge. I don't let them go below 12.00V before recharging them. And converting to all LED lights cuts the lighting power needed by over 80%.
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