Well, if you don't mind seeing your credit tanking, how about a short sale? 

.* If you are moving just a short distance from the current PR and/or moving from a SFH to multi, then make sure you have very good explanation letter to convince the underwriter why they should approve this purchase as an owner occupied.With regards to the financing options, I always prefer conventional, so PMI eventually drops off.

Usually rentbacks call for higher rents than market, not lower. of course, those situations I've seen have always been short term. you make it sound like this can be several months. in that situation, I would tell them they have to pay market rent, and provide security deposit.

It’s short notice, but we will be meeting up with a couple of investors tomorrow at 9.

Long story short use a mortgage calculator.Buying at say 900k at zero down would Be a monthly payment of 5988 a month.

If they claim they never obtained it, they can claim twice the amount of the deposit against me in court.So short of obtaining a scanner to take with me to appointments or bringing duplicate copies to fill out and sign, how would you suggest I mitigate this risk?

It looks like you're short $210,000 plus closing costs. 

I am in contract on a short sale.

He and his wife have recently moved 7 hours away for his wifes health/ allergy reasons and do not want to manage the property long distance. 

Short-term rentals can be difficult to finance.