Is this a fair pre-employment question?

Ok, so yesterday I went on a final interview with a company that sells products to the plumbing industry. I’ve had 3 other interviews and a two day ride along with another salesman with in the last two months to see the logistics on how my job would be handled day to day. I am 29 years old and a single father that has joint custody with my 4 year old daughter. The guy I interviewed with at the end of the 2 hour interview asked me to write up “something” regarding how being a single father won’t affect my work schedule. I asked him what form would he like this request in, my calender, a essay? He replied don’t just email me your calender and a paragraph. Right now I have my daughter every other weekend and every Wednesday. It is making me question if I want to take this job, while it would be a great opportunity for me, I feel as if this initial request is asking too much, if I should have to do this shouldn’t every parent in the work place be requested to do this. Is this a fair pre-employment request? How should I respond? I would really like some advice from the fluther community.