Flower Army Marksman is a pretty hard contract. Your strat was good, but you didn´t distract the golf teacher, he is always a whitness. Before killing the targets i distract him (he turns around) then i shoot the target near the lawnmower. Then the guy going for a smoke. After that i wait until the smoking waiter turns around and goes inside the mansion. That´s the moment where i start shooting target 3-5 from left to right and run to exit.
Like i said, it´s a pretty hard contract and strong RNG, that´s why i didn´t post it anywhere
Here is my SA run