Naomi,
First off, teachers need to learn to be creative and to "think outside the box."
Now, what I would recommend is to create lessons that focus on your client's business needs and give him vocabulary that will enable him to be successful in his business. He needs to learn concepts regarding his business, using the vocabulary for that particular situation.
As far as creating time-consuming lessons, I would not do this as this is boring and will turn off this man from wanting to learn. Instead, use your time with him to role play situations involving different scenarios involving his business.
There will be no getting around your need to prepare materials and activities for him.
Tutoring requires the same work as teaching.