There's one small problem with flying Part 103 in the U.S., and it's the simple fact that the population of the U.S. is 346M, in the same area of land mass as Australia, with 25M people.
It's not like vast areas of the U.S. are like Outback Qld, with 1 person per 1000 sq kms.
And this sums up Part 103 flying in the U.S.;
"While Part 103 prohibits flying over congested areas (defined as one or more people), it can be difficult to ensure absolute compliance, especially in urban or populated areas."
The place is chock-o full of people and aircraft, and you plan flutter around in the equivalent of an airborne bicycle, with no equipment that you can use, to find other aircraft in the vicinity?
Then there's the not-so-small problem that law enforcement in the U.S. is brutal, and you may find yourself in jail for infringements of laws you didn't even know existed.
Add in the litigious nature of U.S. society (whose reach is not limited to America), and if some offended party claims injury or otherwise, and launches a lawsuit against you, you may wish you'd never seen the place.
Then there's the point that virtually every American owns a firearm (or 113), and they're basically very angry people, and they're ready and willing to shoot at anything overflying "their patch!", with high-powered weaponry (AR-15's and AK-47's are very popular), and this could make flying just a little more dangerous than you ever imagined.
I've seen more than one American on other forums bragging about shooting down "nosey" drones, and annoying "noisey" RC aircraft, overflying "their patch".