I am not sure what an inner wipe is. But as I remember on my '81 300SD when I replaced the left rear regulator (to replace the plastic sliding jaw - yes, it has a name), it seems like I had to unbolt and move over a metal strut to get enough room to wiggle the regulator out - or maybe get it back in - not sure.

But I do think that strut has to be unscrewed and moved over. Seems like that strut is just below the back fly window.