You should also consider having enough to satisfy all of your mortgages, debt obligations, and future college expenses for your children.Keep in mind that insurance companies sell term insurance because they are pretty confident you will outlive the term.

In 2009, after the collapse in the housing market and after the banks cut off further funding and called in loans, you were able to buy 1st mortgage debt for .10 cents on the dollar. 2nd mortgage liens were available at 1-2 pennies on the dollar.

You make a good purchase, increase the NOI, pay down some debt, double your equity and move on (via a 1031 if you're smart).

I was wondering if there is a way to use the potential income from one side of the duplex towards debt to income ratio?

I can't ask the bank for another loan, not based on my "Debt-to-income" ratio, or at least I don't think I can.

Apart from finding high cap rates and being okay with being in debt up to your eyeballs, are there any other methods of growing quickly?

Where people get in trouble is when they look at it as a pay day and put the money in the bank to pay for bad debt, trips, cars, bills etc...Use your cash flow to pay for these things, after you have some reserves!  

That won't make you feel like your drowning in debt!

Do I have any debt ...nope, nada, zilch...so the prospect of paying for a house outright was a simple matter of “yeah I don’t want any debt servicing” but I didn’t take in consideration the cost of self financing.

And keep saving and pay off any debt.