I would be interested to see a photo of the part. I had my awning contol fall apart whilst travelling years ago. From memory, a rivet failed. I dug into my toolbox and found a nut & bolt which repaired the awning. It didn't look nice, but did the job. As far as I know, it is still there - I gave my van to an organisation to serve as temporary accommodation following bushfires last year.
That lever looks like it had a slot for a pinch bolt at the end facing the van, have the ends of the lever broken off?, is there a thread in the end of the shaft where the lever sits? If so you could drill a 4m.m. hole thru the lever & shaft and fit a 4m.m. stainless nut & bolt,.