You will be able to find a co-op apartment that allows rentals but whether you'd be able to close on it is another question.Co-ops with poor financials will have trouble selling units to borrowers using a mortgage.

But this also typically requires existing relationship before they will start bending their "standard" underwriting rules.

In order to past this SS test, your appraised market gross rental income at 75% has to be more/equal to your monthly mortgage payment (PITIA).

I've been playing with amortization calculators and have seen you can pay off 1/3 of the mortgage and reduce 2/3 of the duration.

Yea thats what i have found out. but i have a hard time scaling since im not able to cash flow. it becomes difficult to keep adding more properties when you have to cover the gap in rent vs mortgage. 

I have a note in the lease that they're not supplied or warranted by the landlord and the extent of what I will do (if any exist at all) is haul them away. 

Promissory notes in general, as they have no collateral, seem a bit higher risk, perhaps mortgage note investing which are backed by residential and sometimes even commercial real estate would be a safer alternative, and yet very lucrative, too,  8-12% yieldsFor extra returns, I put a small portion of my portfolio into BDCs, Business development companies, that specialize in loaning money to growing businesses which are too high risk to get loans from proper banks.

Although we’re not a local bank or credit union, we are independent mortgage brokers with experience in financing options that consider rental income rather than personal income. 

If the rate is reasonable then it may make sense to try to save fast to get to the 3.5% down payment on a double or triple - househacking may allow you to increase your savings rate and pay down that loan even faster.As for estimating costs, closing in NY factor at least 1% of the mortgage amount for tax, plus $1500-2000 for lawyer, title and fees, then the amount required by the bank for escrow will depend on the actual property taxes and insurance.

I was shown about a handful of their holdings in the Houston, Memphis, and Little Rock markets, but the cash flow and CoC returns were less than $100 per month and 2-4% after factoring in additional expenses like 7% vacancy and 10% maintenance per month to go along with 20% down and conventional mortgage.