No assurance required!
I find it interesting and intriguing to listen to other people's interpretations of our National Anthem. There are a handful of instances where I felt that the arranger did not show respect, but they are rare, and in many cases were clearly written to show disrespect or disdain for the country and the people.
I especially enjoy listening to arrangements by people who were not born and raised here, it adds a new dimension to the piece. It's how other folks view our country.
Don't get me wrong, there is something about listening to the U.S. Marine Band play the piece, especially if it is live and they are there in their uniforms! Their rendition is something of a yardstick, but then consider I've heard them play it more than once<G>.
Then again, I still listen to the Jimi Hendrix version...
So just arrange it as _you_ hear it. If you hear the first and second 8 bar sections as being slightly different then make them different... I doubt that anyone will complain.
(Given that there were "bombs bursting in air" at the time I'm pretty sure F. S. Key wasn't worried about the musical structure.)
It is a song that most American's still take seriously (this summer I took my 4 year old son to a minor league baseball game, when they played the National Anthem we all took off our hats... my son followed suit without being told, though he did ask why later!), but that doesn't mean we don't appreciate someone else's point of view.
Have fun, and please post it here when you are done!