How do lenders view debt when looking at a 2nd investment prop?

[Lem Diaz]

Disclaimer: I live in the SF Bay Area (aka reallllly expensive to buy anything).

Help me understand how lenders view debt. So let's say I purchase a SFH for $800k and put down 160k (20%). So now I owe 640k. For that level of mortgage I'd be paying circa $3200/month.

If I want to purchase a second property for investment, while living in the first one, what are my options for financing? As I understand most "retail lenders" (Wells Fargo, Credit Unions, etc) will want a 43% debt to income ratio to qualify for another loan. So in this scenario lets assume I have a DTI of 50% or higher, but I can still manage to put down 20% on the next investment property...let's say it's another 800k house.

How do investors manage through these scenarios? I doubt a bank would want to give me a loan given how high the DTI would be across both houses.

Would the situation be different if the investment property had a zero dollar cash flow?  Meaning after all the capex, mortgage, insurance, property management, etc are all said and done I even out every month. What about the 3rd, 4th, 5th, etc property? Even if they even out from a cash flow perspective the debt starts to accumulate.

I guess in the end what I'm trying to figure out is how people can convince banks or lenders to give them these big loans when they're leveraged beyond a 43% DTI across all their properties.