I like the idea. Not that I'm changing my TL for your demands or so. But I want to know the possibilities of it. Like, why did it not work out, can it be in combination with what I plan. These kinda things.
The english wikipedia article on the Inca Plan is surprisingly complete. Whta calls my attention is that in TTL some of your changes have affected some fundamental thing about the plan: in otl one the two candidates of this posible throne, Juan Bautista Tupac Amaru Monjarras (brother of Tupac Amaru II), at the time of the proposal in 1816 was being held in a Spanish prison in
Ceuta. Of course, the rest of the family was kill by the Spanish after the failure of Tupac Amaru II revolt, and his brother had been in Ceuta since 1783 in otl, and I don´t remember in wicht year Morocco took it in ttl. Assuming it was after maybe the moroccans just let him go. If it was before he probably is in another prison outside Spanish America. Whats is also interesting about this proposal its that todays sound outlandish but in its time had alot of suport and power behind it: in the Congress of Tucuman this proposal was approved by a simple majority (but failed to win the necessary 2/3 majority thanks to Buenos Aires opposition), it was overwhelmingly supported by the alto peruvian (modern Bolivia) representatives (at the time Alto Peru was part of VR of La Plata thanks to the bourbons but under loyalist control), and also by the representatives of the northern and western provinces of Argentina (all the eastern ones but Buenos Aires were under control of Artigas who had already proclamed independence the year before, and demanded to have the capital be "anywhere but Buenos Aires"), and By San Martín (at the time preparing the liberation of Chile as gobernor of Cuyo) and Martin Miguel de Güemes (Caudillo of Salta and defender of the frontier against the loyalist), so basically the biggest oposition was Buenos Aires but their objection was only centered on the point of moving the capital from Buenos Aires to Cusco. The monarchy was supposed to be strictly constitutional, and the candidate to the crown was really old anyway (Juan Bautista was liberated in 1823 and moved from Ceuta to Buenos Aires, and died in 1827), so the big point was including the indigenous peruvian nobles and peasant communities into the political order and moving the capital far away from Buenos Aires (wicht basically everyone wanted but Buenos Aires).
EDIT: some maps
Also nice map of Mexico:
And Hispanoamerica: