I knew of a case where the buyer agreed to give the seller (an elderly widow) a life lease on the house.  After a few years, she had dementia so bad that she was convinced that he was stealing her farm.  For spite, she would let the doors and windows open during the winter, as he was responsible for the electric bill for both the house and barn (there was only one meter), and the house had electric heat.  Not saying don't do it; it should be a good opportunity for you both, but be careful to protect yourself and him as well.