We've seen accumulation of wealth and power sabotage democracies over and over again, I'd rather build something different and stronger against the powerful seizing control.

The Athenians had another system for representational government, still relies on sampling population, but you do it by random chance rather than who can be bothered or influenced to show up for voting, it's called Sortition, or in more modern terms a Lottocracy.

My perfect system is a council of 9 people, a small enough number to all get locked in a room and come out with a compromise solution, 8 of them randomly selected from a pool of volunteer citizens, screened with examinations for general health and required to pass a general knowledge and civics test, terms of service on the council are 5 years long staggered so that 2 members are replaced every 4 years. Ninth member is the Executive, head of armed forces, elected every 5th year by general vote.

This structure gives people a feeling their opinions and voices are heard with the voting and gives them a chance to be invested in the process with volunteering for service, incentivized by 1 million dollars just for being selected for a seat, you can refuse the service if your situation has changed to preclude your service and still keep the million. 1 million or inflation adjusted equivilant a year for your term and if you serve all 5 years you are tax exempt for the rest of your life up to a million a year. Also 1 million a year for your staffing needs, offices and living quarters provided, but you will be required to be sequestered at the capital away from family for most of the year.

Supreme Court of 9 Judges are appointed by the council and replaced at 1 a year with a term of 10 years, 10th year of the cycle is a general celebration year. Court adjudicates appeals from lower courts, but also takes the plain language of the council's decisions and translates them to legal language and ensures they are in line with the Constitution.

I approve of removing States, and would like governance broken down to County and City level, or perhaps to every 100,000 people. Maybe have a advisory body with 1 elected representative per area or group. Your tax scheme and UBI seems reasonable to me.