Need Advice on Creative Financing Strategy - SFR

[Jerry Rode]

Situation:
A family is looking to rent a larger single family home for up to 2 years (international family on work visa until end of 2013). They currently rent at $2400 per month in my sub-division and want to rent in same subdivision.

A home is for sale by a couple that is moving out of town rather soon. They are under pressure to sell asap, and the international family loves their home and would like to rent. Seller is not looking to rent their $225k home.

I want to buy seller's home at a reasonable investing price and rent to international family for the next two years. Trouble is, I do not have all of the necessary down payment and do not feel that a bank will give me a mortgage on a home if I have to take out lines of credit on other rentals to come up with the down payment & closing. That whole, take a loan to get a loan theory.

Here is where it gets interesting. International family may be willing to pre-pay their rent, providing me with a lump sum as down payment on the home. Does this lump sum need to be 'seasoned' or because it would be written up as prepaid rent a bank would be more willing to write up the mortgage?

I'm open to suggestions!