There is absolutely nothing wrong with spanking.

However, the fact that you can not, as an adult, discipline yourself or hold yourself accountable for your actions, and must rely on your wife for the impetus to do what is right in every day life, may be a problem.

I guess saying "grow up" would be a bit harsh, but to give yourself license to behave in a childish way with the necessity of monitoring by another adult is not responsible, and your wife seems to be uncomfortable with the idea. When does she get to be 'babied' and cared for? Are you shirking your role as her partner by calling her your "coach"?

I urge you to rethink this course.