bd you are probably right on the 2nd part,
No "probably." I'm right.

however the on the first part I don't think so. The law specifically states that your entire body must enter. So if you're above or beside or near you have not entered yet.
You're assuming you have to have feet in contact with the ground to "enter" the property. I believe you are wrong about that. Tennessee property law gives the landowner the power to control his property, "including the space above the surface of the land." There are plenty of cases discussing that.
When a person is on a navigable stream, they are still on the landowner's property. You have entered with your entire body. You just have the right to float through under a public "easement of highway." The law prohibits the landowner from unreasonably obstructing this easement. It cuts both ways - the landowner can't interfere with people floating through, and people floating through can't interfere with the property. As stated by the Tennessee Supreme Court all the way back in 1911 in Miller v. State, "The riparian proprietors also have rights in such streams as valuable as that of the public, and these respective rights of the public and the riparian proprietors must be so used and exercised as not to unreasonably interfere with and obstruct each other." Some people incorrectly say "the landowner doesn't own the stream," but it's more accurate to say the landowner doesn't have the power to obstruct your public right to float through his property on a navigable waterway.
It's never been tested in Tennessee that I know of, but based on what I know of other states, there's a good chance that if push came to shove, a court might hold that anchoring to fish goes beyond the rights granted by the common law easement to float through. The original basis of the easement was to allow the public to conduct commerce on large waterways - back when a lot of goods were shipped by water instead of land. Thus, the original basis would have just contemplated the ability to float through from Point A to Point B unimpeded, which has nothing to do with stopping to fish.
Anyway, as noted earlier, none of this really pertains to "blue lines," since those small streams are not going to be regarded as navigable in the legal sense.
bd