Rental Property For Sale With Paying Tenant

[Michael Emanuel]

I have found a occupied property down south for under 45K. The current tenant is paying $900.00 monthly in rent for this 3 BD 1 Bath. Zillow has the "estimated monthly payments" at $275.00. Could I stitpulate that one of the conditions of the sale be that the curent renters sign a 1 year lease at the same $900.00?  I would be a little less apprehensive with this 1 year lease locked in. This would be me and my wife's first deal. 

A little about myself. I have an 810 FICO score, several credit cards with 50-70k credit limits, a primary residents backed by my VA loan with close to 200k in equity and I still work a 9-5 job. Even with all of this I'm scared I could mess this up.