The way that I have rationalized it is that, if I can lock in an interest rate (say 4.375%) that is below the real rate of inflation (7.5% minimum), in this case several magnitudes, I can come out way ahead.

Those are junk tenants, should be discounted about 50%...You're attempting to rationalize a top quality, Class A building with national tenants and nearly new construction into this low quality office with below 80% occupancy.

You could put your rational together in a attachment to your offer.

I agree with Christopher that the seller is not acting rationally to sell without taking any equity. 

Also, you may want to consider an umbrella policy.I've heard the same advice from various attorney's which in my mind can only be rationalized for ultra-high-net worth individuals.

It's just a way of trying to rationalize the "white lie" because it's hard to factually prove what my intent was when I was filling out the mortgage application. 

In my situation my seller wants me to take the first half the month unpaid rent out of my pro-ration, basically assuming that I will collect it.

You're rationalizing (rationalization is the most expensive word in a REI vocabulary...NEVER USE IT) a bad deal into a good one because it's your first? 

We paid cash for 2 properties now and when it comes time to refi out the banks are saying our debt ration is not good.

I wouldn't rush to pay off anything under 4%, as this is almost free money.if you have high monthly loan payments, relative to your monthly salary you may have trouble finding financing. if your loan payments are lower it may have no effect.remember, this is all a  numbers game. if someone says you always have to pay loans off, that is because they are risk averse and let fear talk. rational investors make decisions based on numbers and facts, not fear and emotion.