Lou,

Do a look up of the stuff I have written and you will get a ton of stuff about lifting tails (it tends to be a fanitical thing with me, sorry). Actually if the CG is between 25%-anything aft of that,with everything else at 0-0-0 degrees, the tail is lifting. It doesn't have to be unstable. It is just the result of the force and moment balance around the CG. Certainly it will go unstable if the CG is aft of the Neutral Point of the airplane regardless of other stuff.

The old (and new for that matter) free flight models with the long tail arms could have the CG as far aft as the wing trailing edge of the wing (and farther but always not aft of the Neutral Point) which meant that the tail was always lifting regardless of speed or usuable incidence.

The wings couldn't input a nose down moment due to camber large enough to need a down load at the tail. With a cambered wing with its nose down moment it does add some moment that might cause a incremental nose down load but the net load is usually up.

In free flight glide you want a dCm/dvelocity curve at the lowest sink rate. This is still a lifting tail. Note that even with the high thrust line models they still used the same tail sections. The high trust line gave a power moment to counter the higher climb speed nose up pitch characteristic from the dCm/dvelocity curve. It did move the tail out of the slipstream somewhat. The variable incidence tail that is used nowadays is basically moving from one dCm/dvelocity curve to another.

The free flighters thought that a lifting airfoil would certainly be more appropriate if the tail was lifting anyway. For a given tail load the choice of a tail section was a trade off of the drag of a flat plate, symmetrical tail, flat bottom or cambered airfoil.