I think the key to plein air painting is to be very selective about what you "allow to be included". You really have to think about each shape "deserving to be there". there's so much stuff out there and it doesnt help to improve the painting necessarily.
there were several areas of junk around the boat and a few extra shapes in the midground i left out when i was out there painting. then when i got it home i painted out a few more and ended up with a sweet little painting of a boat in its environment.
have to remember i'm a painter and not a photographer. the difference between a short story writer and a newspaper journalist. one weaves a tale for you. the other gives you the unpoetic blow-by-blow.