With a POD of 1810, have America own British Columbia, Alberta, Baja, Sonora, Liberia, Cuba, the Philipines, all of the Smaller Pacific Islands and hold them to this day. Japan has to be an American puppet. Major events, like Pearl Harbor, WWI, 1812, the Civil War, ect, must still happen. Also, America itself must keep its current government system and allow some basic forms of Democracy in its Empire.
The problem is that your Major Events stifle the ability of history to deviate, which is exactly what you are trying to do. For example, if the war of 1812 caused long term bitterness between the USA and the UK, its quite possible that the USA does not do "WW1" as an event.
Of the conditions listed, two are met with OTL--Japan is indeed a puppet of the United States (Check out the defense arrangement they have with the USA and Article 14 of their constitution). Finally, the USA generally does own many of the smaller pacific islands.
Basically, the problem you have here is that you don't want to change the course of history but change its outcomes. In essence, you are looking for a massively exploding America without Butterflies. How the USA is supposed to grab New Zealand or Tahiti from their European masters is not really in the cards.
And what would happen is some kind of horrible Historical Bastardization that barely resembles history:
1812: Quebec goes into an uprising in support of France, seizing the opportunity as the United States marches into Canada. The UK is swiftly ejected from Canada. Spain loses Florida and Cuba to the United States as well as the Napoleonic Wars Continue until 1817 (Napoleon Wins at Waterloo). A defeated UK can only scream in vengeance over the outcome.
1820: Historical compromise on the Mason-Dixon Line.
1832: Nullification Crisis in Georgia escalates into a State Uprising. South Carolina provokes a Federal Show of Force, which quickly crushes the South Carolinan Uprising. John C. Calhoun, once the Vice President of the United States, is hung for treason.
1836: Texas Secedes from Mexico--Texas begins to fight a dirty war against Mexico, successfully fending off efforts to reclaim the territory.
1845: With the Full Support of the Texans, the USA annexes Mexico, Triggering a full scale war with the Country.
1848: Mexico City falls to the United States, unfortunately, so does the Mexican Government. There is no alternative but to simply occupy all of Mexico.
1861: Thirteen Years after their complete defeat in the hands of the United States, the southern portions of Mexico rebel. The Mexicans are facing prejudice and second class citizenship, often at the hands of highly racist Southerners. Indeed, one of the most despicable practices is the enslavement of Indians from Mexico proper--a move which draws global condemnation.
1872: After over a decade of fighting a Civil War, the world and Mexico are appeased with a National elimination of Slavery. Cash will pay for slavery in each state and the nation will ban the trade.
1880: An Imperialistic USA attempts to open Japan up for trade; Japan Refuses--after a short war the USA emerges with Japan as its colony.
1914: The USA enters WW1 on the Side of the Central Powers, as rivalry with the UK has become Intense. The USA claims every major Pacific Island as its share of the Spoils, as well as a large swath of the African Coastline and friendly state of Ireland is created at the expense of the United Kingdom.
1941: The Third, and most difficult of the Japanese Uprisings begins. Japanese Suicide Patriots destroy the Arizona and damage other shipping with a "Kamikaze" aircraft. It is revealed that the UK has financed the operation. As the UK falls into an autocratic government, its hawks demand a rematch against the Amero-German Alliance that rules the world. With France and Italy on the side of the Allies and Democratic Powers of Austria-Hungary-Slavonia, USA, and Germany against them, the USA fights a terrible rematch against both a Japanese Uprising and the United Kingdom and France. The United Kingdom surrenders, shortly after nuclear weapons destroy Rockingham and London.
1951: A cold war emerges as the Soviet Socialist Union emerges into global politics--its attempt to provide a leftist alternative to American "Imperial Democracy" and English "Monarchial Hedgemony" is met with some success, as well as a rivalry spawned by Nuclear Weapons.
Present: Super USA and its Ally, SuperGermany stand like twin colossi against the emerging people power ideology, One can only hope that the world avoids the tragedy of London or the Grim Humor of Rockingham.