As a stop-gap measure, I attached some cheap ribbon to the inside of the center-front edge, right below the seam where the cloak met the hood. This was alright, but it seemed like the wool could give out, given enough time.
A search for period images showing fastening methods in detail turned up ribbons and tapes exclusively. I didn't find any buttons or frogs. Since portraiture is almost exclusively of the upper classes, I found many images of silk cloaks fastening with silk ribbons.
Detail - 1780 Eliz. Crompton by Joseph Wright of Derby, Derby Mus. & Art Gallery
In the above image, it appears that the lining forms a casing through which the (very wide) silk ribbon is drawn. It seems unlikely that wool cloaks could be gathered in the way a silk cloak could due to the thickness and sheer weight of the fabric, but it's an interesting image nevertheless.
Detailed depictions of lower class cloaks are few and far between, with the best-known possibly being Zoffany's The Watercress Girl. I never found a high-res image of the original painting unfortunately, but the low-res shows that the cloak, its edging gimp, and the ties are all the same shade of red. (As an aside, I love this picture for the cloak, spotted handkerchief, beat-up silk-covered hat and horizontal pins!)
Detail - 1780 engraving after Johann Zoffany's Watercress Girl, Yale Cent. for British Art
