If the batteries are under the steps, why not on the side panel of one of the steps.
It will keep the 00 cable short.
Can't be handier than that IMO.
I would switch the + wire.
Mike in Colorado
2004 Fleetwood Pace Arrow 37c,(Jezebel) Ultra RV ECM / TCM, Bilstein's, Sailun's & Sumo's all round, pushed by a 2014 Chrysler T&C.