License or Non License Contractor for Bathroom Renovation

I am in the process of turning my primary home(built in 1955) into a rental. The house has some updates but the bathrooms unfortunately are not. With that being said, another house in my neighborhood was being remodeled so I decided to go in. I took the number of the contractor that was remodeling the bathroom and a month later invited him to my home for an estimate on my bathroom remodel. It turns outs that he does not have a contractors license but his work looks pretty good.

My questions is, if I do hire him and he doesn't have a license, can I have him sign some documentation stating that 'he' is liable for any health mishaps so long as he is working in my home?