Being completely honest, I'd say even for an image with the car in focus, removal of the tree would be painfully long and I think you'd find yourself getting particularly bad tempered over it.
I'd chalk it up to experience and be aware of your surroundings for the next time. If you're forced to stand in a nettle patch, take some good strong rugged jeans and boots (not designer crap)
The alternative is to go out to the venue, stand in almost exactly the same place at the same time (hoping the light is the same), take a similar a photo as you possibly can and then layer mask the two together effectively removing the tree from the image.