What size batteries? You may not be getting any more capacity out of two 6V batteries.
As an example, two 100Ah 6V batteries will not get you 200Ah at 12V. You'll only get 100Ah. Most people don't understand that.
Convert to power, it's easier to understand. 6V X 100Ah = 600 Watt Hours
Get two of them, and you have 1200Wh.
Now take a 12V 100Ah battery. 12V x 100Ah = 1200Ah.
6V batteries really only had advantage in being able to put out huge amounts of current... and our campers really don't need that. I run a 100Ah 12V AGM battery and a 100W solar panel. That combo will pretty much run most things without going too flat.
I don't have my 176 quite yet, but I am really curious how much juice it really takes to extend and close the slide out. Since I do a lot of boondocking, I take my 2200W generator.... it would make short work of the slide out, I bet!