[ABC]

Ray B with respect, What you have been told is wrong and goes against every roundabout use guideline worldwide.

There is only 1 correct way to use a 2 lane Roundabout (see: Quote from rockaway)

If the inner lane was for trucks then according to roundabout design the lane would be a raised truck apron, i can see why with your motorhome you may need to encroach on both lanes and i am sure you do this wth care but this is not the reason that the lane was put there.