MFC
Following your tail positioning problem, I suspect that if we could change the tail position of a balanced (read stable) airframe closer to its main wing without changing its proportions we would find it hard to trim and hard to stablize; something like a coil spring with a weak shock absorber: the tail would be bouncing the airframe all the time at the smallest aerodynamic variation. Conversely, if the tail is pushed aft the airframe would have a greater resistance to pitch changing.
GD&L