2 or 4 6V batteries.

Coach-man wrote:
If I understand you, you currently have two batteries, (I do not remember if you listed the amp hours?), and use your generator several times to dry camp for 3 - 6 days at a time? By simply adding 2 additional batteries, I do not think you will double the time between charges, and as pointed out re charge time would go up. 4 six volt batteries would extend the time between charging, I would also invest in solar panels to charge those batteries during the day. That option would give you the most power and greatly reduce the time you would need to fire up your generator. Definitely on the pricey side, but since you do dry camp a lot IMHO that would give you what you are looking for. Good luck.

That's exactly my scenario. I need to charge everyday. Batteries start out at around 12.8v and by the end of the day are around 11.8 to 11.6. I have a 1000w Samlex invertor with a remote digital readout in the 5er that I monitor the batteries with. We usually run the gen everyday for 2-3 hrs around dinner time. Wife likes the hairdryer, so we kill two with one gen run.
My concern initially was how long I could use the 4-6V before I would have to run the gen for way longer than 2-3 hrs. I suppose I don't need to run the gen for 2-3, but that's what I do. I don't want to get my self in a situation where I need to run the gen 1/2 the day to recharge 4-6V. Sounds like either way I go it's just good practice to recharge daily, regardless of the charging method.
If that's the case then I may as well just use 2-6V since I'll be running the gen anyway.