The 55A is for the converter (DC section) and has nothing to do with the AC Source Power.
30A AC Source will be the total amount of AC Load before tripping your AC Source.
30A transfer switch is part of the AC side. Allows 2 different AC Sources but only one AC Source feeding your AC Power Panel
55A converter is amount of DC Load converter can handle before it goes into overload mode (shuts down)......supplying DC System and battery charging.
Don't see specs on that Atwood Model but suspect it is not a 'smart charger' (3 stage). Most likely just a single stage charger.
Boondocking and batteries.....go with a 3 stage converter/charger.
Costs more but much better investment
