I have wanted a frock too, but there is some question as to when they came into fashion. I think that I will go with the 'Match Coat" which is documented by a painting done in 1762 by John Parsons, of a Cherokee chief named Cunne Shote, (also known as Stalking Turkey; the painting is rather famous). He is somewhat fierce looking, and holds a fine frontier knife in his hand. He is wearing a fancy '...Coat' which is really just a cloak.
I ran across this in the Museum of the Fur Trade Quarterly (Vol 33, #4; Winter 1997) in which the article ran ten years ago. The author even included a pattern suitable to making such a grament, the appropriate material and suggested materials to make a fancy version using 'tinsel, or caddis'. There seems to have been a strong trade in cloth for this apparel.
The Match Coat was described as early as 1705 and was widely worn by Indians and the Euro settlers for much of the 1700s. George Washington was described as wearing one in the F&I War in 1754.
Anyone curious, or wanting to make one, can contact the Museum of the Fur Trade in Chadron, NB and inquire about it. Gail DeBuse Potter was the author.
Dick