Personally, I wouldn't hire just anyone to ride my horse.
Is there any way that your trainer can refer you to people?
No one just decides one day to be a trainer and gets clients of the bat, you have to work up to it. I started mucking stalls at a farm and gradually I was allowed to ride a horse there, then it turned into excersizing horses as being a job.
Every great dream begins with a dreamer. Always remember, you have within you the strength, the patience, and the passion to reach for the stars to change the world. ~Harriet Tubman