looks to me like the pic posted is the same dimensions and running board design used for the 3500 roadtrek modification which my 3500 07 chevy has (as OEM from chevy before roadtrek customizes the interior adding the stove, head etc you see in the diagram. ) my comments on my running boards::

I've found it's easiest for older or handicapped folks to enter and leave thru the center door using my portable folding step stool. the running boards are narrow , and I've seen guests nearly trip and fall because their feet don't fit too well especially when they're getting out of the van.

would I pay to add running boards to get in ? no