You do not have anything to lose especially if you just view it as another way to support your church financially. Any business it yields is just gravy. However, if it is just strickly to gain more business I would probably pass.
I bet one of those Catholic churches would agree to let you do seminars for their senior members. I did them years ago. Field and reported as a sales meeting
Especially if you have a Spanish speaking ( or any other ethnicity for that matter). Church. Do the seminar along with someone interpreting for you ( if you don't speak it). Materials are available for multiple languages with most carriers