Stuka depending on where you CG is depends on how much weight you want to add to the tail. Your first question would be the idea situation for a servo. Altough I have never mounted a servo in the tail I have mounted bell cranks and I used light ply for support.

On my edge I used the central hobbies bell crank and mounted it upside down in the tail so that when my servo is pulling I am giving up pressure on the elevators (no rod flexing). I use a single servo mounted at the center area of the CG in main body of the fuse I am using the dave brown carbon fiber rod cut for 4/40 metal rod.
Good Luck

Randy