He’s getting 10% interest and gross income/mortgage payment ratio is very high + he’s getting cash flow sweeps every year so that the total loan amount is repaid in 3-4 years.

He said you can get a $10,000 down payment this way and if they miss a payment on time or violate the contract in any way by not paying, you can kick them out and keep the $10,000 they paid for down payment and do it again with the next person.

.), but I'd likely have to get a partner for the down payment, or just wholesale it to someone.)  

His payments are very minimal (less than $150/mo).

I would try to find sellers who are open to owner financing or pre foreclosures with some equity where you could take over their payments subject to the existing mortgage. 

I'd be able to cover the loan payment based on what I'm typically offered for a housing allowance.

I currently have $60,000 in cash at my disposal and I plan to use $50,000 for the down payment and rehab of the first property. 

And - really shaking my head on this one - why would you NOT be looking at notes and other types of investments that could not only be something for your money to do while waiting for their next outing as a down-payment on a rental but could actually speed you to that destination by growing your money pretty predictably?

Just include that amount in your monthly lease payments.

Example:  Purchase price = $250,00020% Down = $50,000Rehab = $50,000Cash required = $100,000 plus closing costs Mortgage =$200,000 (4.5% APR / 30 years)P & I = $1,013Rental Income = $2,500Expenses (50% rule) = $1,250NOI = $2,500 - $1,250 = $1,250Cash Flow = $1,250 - $1,013 = $237 per monthDo not forget the HELOC paymentIf you do the BRRRR strategy the difference will be in your mortgage payment.