From what I've read from various accounts, including info published by the late Roger Freeman, author and recognised 'authority' on the 8th USAAF, who was around at the time, as a schoolboy, and made copious, accurate colour notes, I'd agree with RAF Dark Green, and RAF Medium Sea Grey. The colour shades certainly look closer to the RAF colours, compared to OD and NG, in colour photos from the period, and tally with the info that the paints came from British stocks.