I would include Charles in the deal. Although Lynch doesn't have huge numbers, he is an exclusive back in a league that doesn't have many and he will always get the work. You don't need RG3 so I say it's a win to gain another WR and a high-tier RB.
Lynch currently is outscoring McCoy by almost 30 points (on one more game, but still) and Lynch isn't playing behind a brutal offensive line or with a backup quarterback. But Lynch faces Miami, Chicago, Arizona and San Francisco in four of the five games out of the bye this week. There is a nice matchup with Buffalo in there and Lynch is pretty much matchup-proof anyways, so this is close, but with Nick Foles at quarterback I believe the Eagles will rely on the run a bit more and there will be a regression to correct the lack of touchdowns. I feel McCoy finishes strong.
Not my writing, but it specifically pertains to your predicament.