I found these two books to be helpful....How to Read a Rent Roll - John WilhoitThe Due Diligence Handbook for Commercial Real Estate - Brian Hennessey

Your vacancy expense could be quite significant and consume all of your profit and even get into your principal.

And it seems baffling there are no construction or architecture firms dedicated to the concept.There is no convention in shipping container construction, therefore every step of the process is clunky, i.e. time-consuming, i.e. expensive.This is why, I believe, it hasn't (really) worked, which is definitely not to say that it won't work.

We have used various methods to save up for down-payment funds: we set aside pay raises instead of consuming them, re-enlistment bonus sums, tax-free income from deployments, an inheritance check, the tax-free savings account while deployed...And so forth.  

This issue is still being resolved I believe.A L/O that is with an occupant and where rental credits are applied is a financing agreement, you need to follow Dodd-Frank and Predatory Lender Laws with consumers (your tenants). 

Let's say you can consume 2 hours a day of podcasts.  

@Bryan Otteson Below is the except from the FHA handbook."

The Consumer Financial Protection Bureau alleges that ITT also misled its students—a charge the company strongly denies.

There are certainly issues including how many and what types of properties you can sell with these methods and to whom, but most of those are consumer protection issues.  

Consumer dealings are the bread and butter of the big banks and the banksters who run them.