So, in your considerations, I would park right there for a bit and determine how this would look for you.Since you have about 2.5 years to think about it before you would need to spring into action to take advantage of the rollover for tax advantages, maybe you try on a rental and see how it fits. 

Bear in mind that the fiscal treatment of the two options in Mexico is different (withholding tax on the gross income with the fideicomiso vs cost deductions with the corporation).

I've been using the GE  GFW148SSMWW // GFT14ESSMWW models which comes to $1,650+ tax for units and stacking kit. 

From a tax standpoint, there are additional disclosures to make when selling a business asset for less than fair market value to a related third party. 

I agree with the others here that say you need to have some skin in the game, if you are going to live there yourself, get an FHA loan rather than owner financing, you can get a 3.5% down loan, personally I do not love these as they require  PMI which is an additional expense, and you also need  bring additional funds for closing at least for taxes, title, attorney and transfer fees . borrowing from anyone else for the down payment, to include a personal loan from the bank is not a good idea, those again will be higher int. rate.

He is very good about deductions on tax returns so his income looks negligible and of course banks wont talk to him about loans.

The 1031 exchange will indefinitely defer all tax on profit and all depreciation recapture.

Some homes even come with tax breaks or city funding to help cover the costs.

A HYSA pays 4.5-5%(before rates went down) pre-tax, 3% net tax if you're a high earner. 

To Sum it up, its a good idea if you can exceed the cost of capital (higher rate than your cost of debt) with what you earn on your heloc/debt you pull out and invest.The question is how much gains above is enough to substantiate the risk of your variable interest rate, well thats up to your personal investing criteria.