Buying a house 20k cash with 10+ year tenants current on rent?

[Zayne Yocum]

I'm currently in the process of negotiating a deal for buying a house cash for 22k. The house has tenants that have been there for 10+ years and never missed a payment of $525 as well as paying their own utilities and lawn care and plan to stay. Unfortunately the house is in rough internal condition. Based on pictures I'm estimating 20k worth of rehab but want to keep the current renters there as long as possible due to the fact that I'm already gonna have re due cosmetics whether they move out tomorrow or in 5 years. The ARV I'm estimating at 55-60k. My credit isn't good enough to get a loan right now but I have a good job and am able to put $2,500 a month into savings. This is my first house as well as first rental. Advice?