I run a successful interior design business and some of my clients are developers. 

This will invaribly be different for each rate and scenario but just a general gauge.Even though rates are in the 3's and 4's the monthly payment or what we call the "mortgage constant," on our end is higher because your payment does not consist of just interest, but interest and and 1/360th of principal on a 30 year fixed loan which is designed to amortize/payoff to $0.00 balance by year 30 or 360 months.Typically a rate around 4's will have a monthly mortgage constant of around .50% monthly (6.00% annual) or about $500 per month for every 100,000.Sometimes when the rate gets into the high 3.50% range the MC is around .45% per month ($45 per month for every 10,000 borrowed) so it doesnt vary much while at 4.50% 30 year fixed the MC monthly is around .507% or $50.70 per month for every 10,000 borrowed.I suppose all this technical speak means is that if you borrow money where the outflow out of your pocket is around 6% with interest and principal considered then you'll probably want to reinvest it somewhere else where you can get considerably higher rate of return on this cash than 6.00% atleast this is how I look at it.If you want to make 6% + 6% for cost of funds then you'll want an investment with a hurdle rate of 12.00% or higher cash on cash as an example.

My wife has been in prop management for most of her adult life and is a regional manager for a large company so I plan on using her skills on the management side (why didn't we do this much sooner!!).

When building new, it is possible to design and build houses, and larger buildings, with a modest increase in up-front capital (10 - 15%) costs in comparison to the "normal/typical" minimum code build, which have resulting energy consumption 70%+ lower.  

You may also be able to curate an agency designation from certain companies (i.e.

A fund with a 36 month investment horizon does not really sound like a portfolio designed for cash flowing assets per se, more like a non-performing portfolio.  

Might try to get a working young adult or a grad student for the house manager. 

They are designed to gain wealth only for the fund companies and brokers (sales guys).

@Scott Taylor  the manufactured homes laws are federal.. so they apply in each state although some jurisdictions may have further limitations on a design and build that preclude those.Like in Charleston were I am building in fill there is a project called Hunley waters.

Now I'm destined to invest in real estate to provide housing for intellectually disabled adults.