We can build about 30 of them, limited by usable land for septic.

Some HOAs don't allow you to, and others have a limit as to how many in a neighborhood can be rented.Second zoning: are you allowed to convert your property to a two family.  

Let’s start with the math.Purchase price: $760,000Conventional loan limit for area: 647,000I was looking to put down 5% of purchase price: 38,000This leaves me with a discrepancy of $75,000.This will be a house hack with incredible upside potential and appreciation.

For instance you may want to limit the value of each to 1mm , which could be 10 properties worth 100k each or just 1 property worth 1mm.

With longer occupancy and nominal rent increases each year, you can reach and surpass the 1% rent to price ratio threshold.The biggest mistake I see investors make, and I mean no offense to anyone because after 20+ years as an investor I still make mistakes, is that they don't consider the quality of the area, the home or the management of their asset when trying to hit the 1% "rule".  

Also, you are living in the property which should negate the limited liability of the legal entity (consult a qualified professional or two).Legal entities such as a LLC are not eligible for conforming residential loans. 

Not sure if its outside of the 3 or 6 years limit, but it will create another sale he/she should be reporting this year. 

Based on your limited info my answer would be sell it, but it sounds like the trust or will is preventing you from doing that.

In the area where I would like to purchase next there is a conventional loan limit of $647,000.

It seems like in today's real estate market with limited supply, it is extremely difficult to appraise or accurately value a home (especially in New England/ Great Boston area where I'm from).