Do I write it to a person?

I have a proof of concept web page and can provide a personal story and touch.

I would open an LLC establish an EIN, open a business checking account with major FDIC bank. 

For me personally I did and do the latter land development and new construction along with all the entitlement work and horizontal then build new construction. 

I spent 25 years in commercial construction and you learn something new everyday and its a very difficult business to be in. 

However, finding the right fit for you and vetting that person is going to be extremely important. 

Personally I don't really care for the upgrades.

Person to person deals will always be fine because those are arms length if neither person has a license.

There are no laws, rules or regulations preventing any foreigner, American or otherwise, to buy property in CDMX or Mexico for that matter.If, by having success, you mean getting a profitable investment, I'm sure many American and other investors got that over the last few years (I personally haven't since I've focused my efforts on Mexico's beach markets, which are far better in my opinion.

If you're basically asking this third person to loan you money for the downpayment, why don't you do just that?