I originally was going to talk about The Buffalo Massacre and how we should deal with similar crimes like that, but decided to save that for another time and instead talk about ways for The United Kingdoms of America to be Self-sufficient. Here's some of those ways:
Joint-Stock Company: this is one of the most peculiar examples of Self-sufficiency in a Constitutional Monarchy. Take for example, The British East India Company. This is basically due to Great Britain trading Goods and selling stocks to make a profit (However I might be wrong).
Sovereign wealth Fund: This is the most obvious way a Constitutional Monarchy Government in America could be Self-sufficient. Saudi Arabia and Norway are some prominent examples of countries with Sovereign wealth Funds. They are basically State owned investment funds that invest in real financial assets.
The Party's CEO, Austin Pomper, suggested something that could work. Known as an Imperial estate, This allows the Monarch to maintain personal assets and build up their wealth. The term originates from The Roman Empire and is possibly inspired by them.
Trading Goods is one way to be Self-sufficient and we could probably start trading some resources and importing and exporting our goods to the world.
That's all I can think about for now.