Isn't that Granite Gear fly rather expensive for a sil-nylon fly of that size?

Here's another possibility: Put up a want-to-buy (WTB notice) here for another Clark fly. They are not much to the taste of people here, at least not the smaller ones; and one or more may have sold for <$60, iirc.

Clark's allowance for NOT taking the fly as part of the package is small, so some Clark owners may have kept theirs, in unused condition, as a back-up, while moving on to larger fly's / tarps.

I am myself putting up one of the "XL's" from the previous generation most nights, one complained of as small, and even though I have one of Clark's largest Vertex fly's on hand. I find no loss of function from buttoning down its narrow beaked foot end in blustery weather; and the view and coverage of the head end is more than adequate for sleeping purposes. Of course, it is long enough for your Clark NA.