Save for the immigration policy this sounds a lot like a federalisation of Honduras, for German states (btw, 3 of them are city states, and a 4th is close) already have such competences - including some treaties with foreign countries and their own embassies to the EU (Brussels).

The model cities do also sound a lot like the special economic zones for foreign investment that were so successful in Asia.
Their success depends on political stability, though. Low capital crime rates would help as well, and Honduras has a problem in this regard.