Claire,
Don't waste hours calling the BMV. Your county has that information on record from when the house was converted to real estate.
I deal with this scenario often and Mr. Allison is correct that your Loan Officer should be doing the grunt work; that's what you are paying for.

I had to do this once before. I am pretty sure I had to go to the DMV and get a letter from them showing that there was no title on record for the serial number. That was the best I could do at the time but my underwriter was okay with it. Remember, manufactured homes start off as vehicles and then get converted to real estate once they are set up on a permanent foundation. You should ask your loan officer to call the underwriter and describe your current scenario and get some assistance to the problem as to what they specifically want to have that condition satisfied. It may not be fun but you should be able to get it done.

The county Auditors or Recorders office will have that.

Good Luck!