Rob,
As others have pointed out, there were no "Hessians" (or other German troops) involved in the North American part of the SYW, aka F&IW. However, if you do want to go down the AWI route for your skirmish project, there are some very interesting units in the northern theatre AND you don't need to paint up any more redcoats to go with them, if you don't want to. Also, any Indians and American militia/civilians you paint up will work for both wars.
From 1777 onwards, there were a lot of raids into upper New York from Canada (Quebec Province) involving a mix of Hesse Hanau jaeger, Indians, Loyalists (ie militia types), and semi-regular units such as Butler's Rangers and the King's Royal Regiment of New York (green coats for most of the war). I can give you more details if you want.
All the best.