Hopefully my one-eyed opinion is valid as my other half is Cabin Crew for an un-named national carrier but to my (discrete) experience, once the doors are closed the CSD has a fair amount of flexibility with SLF placement (I luv 1K!
).
Moving people around before push-back is a pain as the crew are run off their high-heeled little feet looking after specials, infants, morons etc. But smile sweetly, make no loud american-style demands and you never know your luck.
Old Japanese proverb says:
"A little politeness costs you nothing but a little rudeness will cost you dearly".
And don't get drunk.