With lower interest (4%) and higher income (reduce vacancy to no more than 5%), you'll find that this is a very profitable property.Plus you're not accounting for the principal payments which will add another $15,000 or more.

They are:RELOCATION - A Borrower may be eligible to obtain another FHA-insured Mortgage without being required to sell an existing Property covered by an FHA-insured Mortgage if the Borrower is:  relocating or has relocated for an employment-related reason; and  establishing or has established a new Principal Residence in an area more than 100 miles from the Borrower’s current Principal Residence.INCREASE IN FAMILY SIZE - A Borrower may be eligible for another house with an FHA-insured Mortgage if the Borrower provides satisfactory evidence that: the Borrower has had an increase in legal dependents and the Property now fails to meet family needs; and the Loan-to-Value (LTV) ratio on the current Principal Residence is equal to or less than 75% or is paid down to that amount, based on the outstanding Mortgage balance and a current residential appraisal. 

The repayment terms for a 401k participant loan are equal monthly/quarterly payments of principal and interest (typically prime plus 1%) over a 5 year term (longer if used to acquire your principal residence).Please note that if you take a full $50,000 and then pay back the loan, you can't take another $50,000 until 12 months after the first loan was fully paid back.Per the loan offset rules that went into effect with the 2018 Tax and Job Act: if you leave your job and the loan is current at the time you leave your job but then the loan goes into default because you left your job, you will have until your tax return deadline (including any timely filed extension) to make the loan current by depositing the outstanding balance into an IRA (and thereby avoid the taxes and penalties that would otherwise apply).

Principal (not principle) paydown generally is a sign you're de-levering investments that are sub-optimal save the leverage. 

$ (100.00) Principal Balance $ 157,000.00 Investment $ 70,000.00 Equity $ 103,000.00 Over Paying PMT $ (727.09) Management Fee $ - Net $ 494.58 Yearly Net Income $ 5,934.90 Taxes Month $ (204.33) Yearly Net Operating Income $ 3,482.95 Vacancy Rate 8.33% NOI with Vacancy $ 3,192.71 Cash on Cash (Are you getting a good ROI) great is 15% 4.98% 1% Rule (Is it a good investment generally?)

Wealth is created with with equity, de-leveraging principal, appreciation and taxes.  

In addition, you may want to have your lender write a letter that indicates you are a principal/partner.Abel 

The repayment terms for a 401k participant loan are equal monthly/quarterly payments of principal and interest (typically prime plus 1%) over a 5 year term (longer if used to acquire your principal residence).Please note that if you take a full $50,000 and then pay back the loan, you can't take another $50,000 until 12 months after the first loan was fully paid back.Per the loan offset rules that went into effect with the 2018 Tax and Job Act: if you leave your job and the loan is current at the time you leave your job but then the loan goes into default because you left your job, you will have until your tax return deadline (including any timely filed extension) to make the loan current by depositing the outstanding balance into an IRA (and thereby avoid the taxes and penalties that would otherwise apply).4) As an alternative to taking the loan, you could even purchase the investment property directly using funds in your Solo 401k (assuming you are self-employed & select a Solo 401k plan provider which allows you to invest in real estate).

The repayment terms for a 401k participant loan are equal monthly/quarterly payments of principal and interest (typically prime plus 1%) over a 5 year term (longer if used to acquire your principal residence).Please note that if you take a full $50,000 and then pay back the loan, you can't take another $50,000 until 12 months after the first loan was fully paid back.Per the loan offset rules that went into effect with the 2018 Tax and Job Act: if you leave your job and the loan is current at the time you leave your job but then the loan goes into default because you left your job, you will have until your tax return deadline (including any timely filed extension) to make the loan current by depositing the outstanding balance into an IRA (and thereby avoid the taxes and penalties that would otherwise apply).

Therefore, you need to know the maximum the rate could increase at each point, when you will start paying Principal, and how those changes in the monthly payment would effect your cash flow or overall deal.