Sequencing four acquisitions when property two is the one that breaks DTI, not property three

Running the ladder out on paper and the failure point isn't where I expected.

Property one: 340k, 3.5 percent down FHA, PITI plus MIP at 2,650. Market rent 2,450. Property two target: 385k, 5 percent conventional, PITI around 2,900.

Income is 168k gross, 14,000 a month. No other debt. At a 45 percent back end I've got 6,300 of capacity. Property one at 2,650 with 75 percent of 2,450 credited back is a net 812 hit. Property two at 2,900 puts me at 3,712, so it clears easily. Property three is where I expected trouble.

Except property one's rental income can't be used at all until it's on a filed return with two years, per two of the three lenders I've talked to. Without the credit, property one is a straight 2,650 plus 2,900, which is 5,550 of 6,300. Property three is dead on arrival and I haven't even bought property two yet.

The third lender said they'd take a signed lease plus proof of the security deposit clearing, with the same 75 percent factor. Which is an enormous difference in outcome based purely on overlay.

Question for anyone who's mapped this: is there a reliable way to identify the lease-accepting lenders before you're three weeks into an application? And does the MIP on property one being permanent for the life of the FHA loan argue for refinancing it out to conventional the moment I have 20 percent equity, or does resetting the amortization and paying closing costs on a 340k note eat the benefit?