I have the downpayment! Not the DTI... Advice?

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Right now I'm a 3rd year university student working a part-time job (25-30 hrs per week during summer and 15-20 during academic year). I only earn 12-13k a year before taxes. I only opened my first credit card a couple of months ago (should have done it sooner) and my current FICO score is 667. I live with my parents and I generally don't have expenses besides personal leisure. I have 5k in savings and there are properties that I am eying on Zillow (should I use an alternate search engine?) that are in the range of 70-90k. They are urban area condos. I want to use short-term rentals (like Airbnb) to finance this mortgage since the rate of return seems to be better than regular long-term rentals (for studios or 1-2 bedrooms) so that I can establish an equity credit line (if I understand correctly) and save up a bit more money and have a head start for when I graduate university. Nobody that I know is willing to cosign a loan for me, but my parents are willing to take furniture out on credit for me if I decide to do the short-term rental gig.

Of course eventually I would love to get a mortgage for a multifamily home to rent out to multiple tenants especially since there is a lot more hassle with short-term rentals, but I don't think that given my economic situation I can get a multifamily.

Anybody have any advice on how I should start out through rentals, not wholesale or flipping? 

Thanks.