If "John Smith's Towing" is not a sole proprietorship what is it?
It's a towing company, silly! (I could not resist that.)
Cape Codder's question simply points out that the fact that the towing company has a business checking account doesn't mean it's not a sole proprietorship. If it's not a sole proprietorship, is it an LLC, a corporation, a partnership? You (BSAN3rd) need to know if the trucking company is a legal entity separate from John Smith to complete the CTR correctly.