Your rent history will determine how a lender decides to include the income or not in a your DTI.

If so, get a 12 month history of expenses. 

When they run a report on you, you need to know what on it before they do.To understand how these behemoth credit agencies came to life, I'll share background on them.The credit bureaus themselves have interesting histories.

I want the freedom that real estate has the potential to give, and I want something that I can share with my daughters when they get older.

The present owner has told you they pay late and that they would never qualify due to their credit history.

I truly believe that this partnership will work , he's an incredible person (lol if he weren't- he wouldn't be marrying my daughter-lol)I do understand what you mean about partnering- there are inherent risks.

A good HML would never give a blanket POF letter unless you had a relationship and history with them.

I ask because I know with some the particular area in Maine as well as rental history will make a huge difference

For example, sometimes if you look at the listing history for a stale listing, you can see a pattern ... as in, the seller/agent has reduced the list price by $10k every month it doesn't sell for the last 3 months ... then, if you see a pattern like that you can get a feel for if/when it will get down to the ballpark it needs to be price wise ... make a mental note to check back around then, and you can then put an offer in the night before you expect them to drop their price again, with the anticipated price drop, plus an additional smaller price drop to get you a great deal ...

Also the recent payment history on the husband has been good.