Having two A/C circuits allows use of the full 30A capability from shore power if one chooses to install that, without using a lot of more expensive 30A hardware and wire. After the 30A inlet and CB, everything on the two circuits can be either 15A or 20A with hardware from Home Depot much cheaper than things capable of carrying 30A. Just remember to separately protect each of the circuits with a 15 or 20A breaker, something I failed to do in the beginning.
I made the mistake of trying to continue the 30A circuit further than necessary and spending too much. My 40A rated master switch was about $40 and the 30A GFCI was more than $100. Both ordered online. Two 20A GFCIs would have been less than one-fourth the cost of the single 30A one.
Bill
