Why pay 100% of your mortgage when someone else is willing to pay a portion of it for you?

I think a major portion is many people do not have the time, discipline or budgeting skills to continue down the path and picking up deals.

My biggest concern is that there are no similar comps in the area over the last two years and a large portion of my investment money will get tied up in one project.

Maybe you can do a portion as short term rental.Are they at market rent, or is there room to grow there?

https://www.cnbc.com/2020/07/08/32-percent-of-us-households-missed-their-july-housing-payments.htmlAs the economic fallout from the coronavirus pandemic continues, almost one-third of U.S. households, 32%, have not made their full housing payments for July yet, according to a survey by Apartment List, an online rental platform.About 19% of Americans made no housing payment at all during the first week of the month, and 13% paid only a portion of their rent or mortgage.Renters, low-income and younger households were most likely to miss their payments, Apartment List found.

So my principle residence sits on 4 acres and I have someone interested in exchanging some of my unused portion (1-1.5 acres) for a rental property.

In addition to that, if you owner occupy one unit, a huge portion of your projected gross rental income will be used to help qualify you for the loan to begin with!  

Yes, you should check with the sponsor to determine if your ownership is kept in place after the refinance, or if it's restructured to a smaller portion of ownership after your investment capital is returned, or something else.  

@Joe Splitrock, good point at least the portion used for personal use would not be deductible (the student loan pay off). 

If there is an ongoing hardship, there are other options on top of the payment deferral such as deferring a portion and doing a loan mod.