Refi to get cash flow?

[Steven Merenberg]

I am half way through my 15 year mortgage on my one and only rental (so far). The rent pays for the mortgage, taxes and insurance. $1,000 in and $1,000 out every month. I owe $71,000 and it's worth around $120,000 with a 3.5% interest rate. I have been toying with the idea of refinancing to a 30 year to get about $300.00 a month cash flow, but the rate would probably be closer to 5%. Is that a terrible idea?