I drew this while watching the season five premiere of "It's Always Sunny In Philadelphia" last night. I'm not sure who the other Sunny characters are as Muppets, but Charlie has to be Gonzo. It makes too much sense. It's funny because just the other day I watched the episode (on my new sunny season four dvd) where the guys try to figure their roles far as the group dynamic. Charlie of course is the wild card.
It's also worth noting that just recently the name of the next Muppet movie was revealed to be "The Cheapest Muppet Movie Ever Made" which is funny to me because the Sunny pilot was famously made incredibly cheaply. Though nothing more than the title for the movie has been announced, there was an idea for a Muppet movie that I believe dates back to the 80s that involved Gonzo blowing all the money for the movie in the opening credits, thus leaving the rest of the movie to be made with nothing. Sounds like something Charlie would do.