For what it's worth.
Saw a Gary L's Prevost in Canada. He used (2) amber reflectors -- one over the other ... which I believe covered the holes.
I had the same issue on our MC-8. I did that for one of the lost/broken reflectors and actually (personally) prefer the look of two oblong reflectors to the one big circle. I am replacing them all that way. It neatly covers the old holes. Factory original? No, but not sure that's a big issue with some busnuts.
Also doing the old Yankee turn signals, which (although) I have found, also prefer the look of (2) oblong turn signals to the one older metal housing.