It sounds like a good plan to me. An attack originating from the lake is a concern, but normally your greatest concern would be an attack from the land side. Small roads that can be easily blocked and living some distance from a large population center would alleviate much of that concern. Although there will be a draw to the location because of the fresh water, Tennessee does have allot of fresh water sources that IMO would dilute that draw. In the end, my advice would be to plan on falling back to the lake house, and take extra steps to defend against an attack from the lake. Dogs, a green chain link fence, and be prepared to install traps and pitfalls.