Not trying to be contentious, but FNMA thinks that 45% is the maximum DTI on a "conventional" mortgage .However on HomePath it is 55% with a DU approve. Perhaps these other lenders are thinking of FHA, which will go to 55%. The difference between 45% DTI and 48% DTI could be bridged in a number of ways.
If the property does not happen to be a Homepath, I would recommend to just offer less, who knows maybe they will accept your offer. This is the easiest and most cost efficient way to handle this issue.
Also we could perhaps do a 3% down and buy down the rate with the other 2% you would have put down. Sometimes that will work, sometimes not.
Also I would go in and see if I could do some sort of alternative MI or buy down the rate to make it work. We do tend to have lower rates than most other lenders so that by itself could bridge the gap that small and put you at the 45% you need.
Here is the thing, you do not want a lender that is going to say sure they can do that if they can't. Loan officers are under real pressure to produce loans and sometimes are too optimistic. Unfortunately, many times the loan officers are likely to say yes when the underwrites says no. Here on Trulia you will find countless posts of people who got to closing, had t he lender pull out of the loan, leaving the poor buyer to scrap with the seller over their good faith deposit.
Also, trying to make the debt ratios work, some lenders will be tempted to work with a short term lock in because the rate is lower and makes it easier for the numbers to work. But what if rates go up?
It is important to get the approval correct, as mortgages that do not close often end in legal problems and lost good faith deposits, not to mention the stress.