Nice to see another TT guy...
For two days batteries are cheaper than solar power.
One of the facts to consider is that solar power is dependent upon sunshine. So, works better in LA or Miami, than in Seattle.
I figure I need around 100 Amp-hours a day in the fall in Minnesota when the days are short (=lights on for more hours) and the nights are cold (=furnace running). In June I would use very little by comparison, maybe 20-30 Ah a day to run controls, water pump, and a few lights.
How much can you expect from the panels? I dunno. Maybe half an amp hour per day, average, per rated watt, in sunny places. Panels run $3 and up per rated watt, plus brackets and charge controller. I'd spend the money and put in 300 watts of panels and call it good if we had sun here, which we don't.
A disadvantage of Airstreams is that the curved design limits the number of panels you can install, especially if you have two A/C units as I do. I'm guessing that you can put up as many as you're willing to pay for.