“would it be possible to hold a job in the us government other than mayor, congress, senate, type of positions, maybe even be required to frequently travel to foreign countries and still be shomer shabbos? “
I know a civilian employee of the Defense Department who does just that.
“I must note though that some disagree with me on that, regarding Shabbos”
There are lots of kulot for national security work. But not all rabbis know them. Find a knowledgeable rabbi, and good luck!