using 400 watt solar kit w/ extra battery I already have....

So, I could set the 2nd battery on the platform (that's already on the back of the RV), hook it up to the inverter with the two thick cables (and a fuse), plug the RV power cord into the inverter? (with an adapter plug to take the 30-amp RV plug down to the "regular" outlet on the inverter?)

I'll assume for now that 400 watts worth of solar panels in the Texas sun :) will be enough to power the inverter and then through the converter to the other battery, if I'm visualizing this correctly.