Officially, all three of the State Lines represented at GCH should have had blue faced scarlet. In reality, because all three contingents were ad hoc amalgamations of decimated units and new recruits, it is doubtful if any regiment had a "uniform" in any real sense.
The 1st Maryland (1780) was formed from the provisional battaltion created out of the remnants of the Maryland Line after Camden; most of the original regiments seem to have had the blue-faced-red uniform issued to them at some point, although probably not in sufficient numbers to clothe the whole unit. The 2nd Maryland (1781) was formed from the Extra Battalion formed in the State and sent south after Camden; it is not known for sure what clothing they were issued (if any) prior to moving south. As far as I can see from Katcher's
Uniforms of the Continental Army, there were no major clothing issues to Maryland troops between March 1780 and June 1781, so I would assume that both GCH regiments were wearing whatever had survived the intervening 12 months and anything else they could get hold of. Possibly most of the R&F were in hunting shirts.
From memory, I believe the Virginia troops were raised relatively recently and - despite being often described as "4th Regiment" and "5th Regiment" - were most likely drafted militia, rather than Continentals proper. On that basis, they were almost certainly not well clothed and equipped at this time, so they may well have had a mix of official, non-official and civilian clothing.
I also seem to recall (possibly from a Company of Military Historians plate) that Kirkwood's Delaware company wore hunting shirts and white one-piece gaiter trousers with a blue stripe. However, Katcher indicates that they also received a set of small clothes and a short coat (I would guess either blue or brown) from North Carolina clothing stores.
Perhaps this site might help you with the overall appearance of your army. Although better known for his ACW stuff, Troiani is usually fairly accurate (and his site is a great resource for AWI uniforms and civilian clothing generally). His portfolio includes an Extra/2nd Maryland figure, but this is for 1780 - whilst unlikely, it is just possible that the unit had received a different uniform by March 1781.
http://www.historicalimagebank.com/gallery/main.php/v/album01/album15/Maryland_Extra_Regt_1780_2nd_Md_Regt_jpg.jpg.html
Maryland officer. However, be aware that officers usually had their own uniforms made up for them, whilst NCOs often got first pick of whatever clothing did arrive, so whilst they are indicative of the official uniform of a unit, what they wore is not necessarily representative of what the R&F would have worn.
http://www.historicalimagebank.com/gallery/main.php/v/album01/album15/TRW50+-+Maryland+Continental+Officer+1780.jpg.html
An example of Virginia State troops at this time:-
http://www.historicalimagebank.com/gallery/main.php/v/album01/album15/Gaskin_s_Battalion_1781.jpg.html
A general view of infantry uniform:-
http://www.historicalimagebank.com/gallery/main.php/v/album01/album15/TRW21+-+US+Continental+Inf_+.jpg.html