Use your Alternate History prowess to keep either Mexican Empire (1st or 2nd) as a country to this very day. Bonus points if Mexico is a regional powerhouse and does not suffer any of the current unrest.
The provision in the 1819 Treaty calling for a Emperor, was designed to allow Carlos' younger Brother to take the Throne.
Iturbide only took the Throne after Carlos forbid his Brother from doing so, and the Mexicans couldn't talk any other European Noble into the Job.
So Carlos doesn't change his mind, the Brother takes the Job, Some problems in the first couple of years between Royal's and Mexican Constitution.
Compromise Constitution rewritten in mid 1820's [displeasing everyone -as best compromises do] Mexico settles down into stability.
To solve it's Bankrupt Coffers, it sells Filibust Texas, and Northern California [36'30"o] to the US.
In the late 1800, following the completion of the Suez, Mexico builds the Nicaraguan Canal. Paid for by the 1879 discovery of Gold in California.