This is the place to post questions and discussions on usage and style. The members of the Wordwizard Clubhouse will also often be able to help you to formulate that difficult letter.
I wouldn't say it was wrong but I don't think it's perfectly okay. It doesn't seem natural. The terms xxx-deep can change meanings depending on what you are describing. Knee-deep can mean quite deep if you are talking about walking through pig manure. If you are talking about doing a high-dive into a pool of water...it's not very deep, at all. As far as getting into someone's business, I'm not sure how meddlesome knee-deep would be... certainly not as bad as neck-deep or even ass-deep...ACCESS_POST_ACTIONS