@Quan Booker be careful:
my hair stands up when I think about partnering up with a tenant, that has bad idea written all over it. Most likely your neighbor does not have an investor mindset - he wouldn't be renting for 5 years.
The ratio of $850 rent to $160k does not seem right. For 2x850 rent the price seems very high. You can PM me the address, I can tell you what I would pay. If he puts it on the market he will pay 6% in realtor commission, that's 11k. Plus he's not going to get asking price based on 850 rent.
Your student loan should not keep you from qualifying for a personal residence. I assume there are other reasons that ad to the total picture. Your bank owes you an explanation if they turn you down. Don't forget to count both security deposits to your down your down payment.
If you want to buy it and you can confirm its a solid deal make an agreement with him and ask for some time. You could sign an option to purchase. In the meantime get your credit cleaned up and think about how you can earn some extra bucks to get the down payment saved up.
By the way, as an investor your goal is to buy below fair market value and not full retail.
Good luck.