Orion and I must've learned the same stuff.
In general, a conventional layout would be negative lift tail. A little corner of the envelope can be in positive lift, but not much...
Once you get your CG aft of the neutral point, if the airplane wanders off slow enough, you can keep up with it. If it is fast, you can't.
Three anecdotes about aft CG:
In the 90's, a twin engined jump plane (Twin Beech if memory serves) crashed in a flat spin, with only a couple of the jumpers getting out. It seems that rather than queueing up from the door forward, and then wrapping aft when the queue hit the cockpit, they had queued up from the door to the aft bulkhead, then wrapped around to the front. This drove the CG aft. The jumpers that made it out of the bird reported that the airplane was riding a roller coaster with it pitching up gently, then down gently, then up on a period of a several seconds. Apparently the pilot was able to detect the pitch deviation, put in some elevator to counter it, then catch the next one, and so on. Then, as the first jumpers exited, the queue bunched up and shifted aft... The lift required of the tail apparently became more than it could carry, the tail stalled and sagged away, and the twin entered a flat spin all the way to the surface. A couple of divers were outside when it started, and a couple more got out, but the crash killed everyone else...
In 1995 a Sonerai was built by a guy (a division chief engineer at a major automaker) who decided to change from VW to O-200 power, change from taildragger to tri-gear, both of which shifted the CG way forward. He then calculated his cg shift and placed a weight in the tail to correct his CG. There were no records of his ever having weighed the ship nor establishing CG. His high speed taxi tests were reported to have included the airplane alternately banging the tail skid and the nose gear. It apparently was not even stable with the mains on. He flew it anyway, trying to keep up with it tried to pitch up, then down, then up, until it got away from him. Lawn dart. Evidence of where the CG was during the flight was now anyone's guess, but it sure looked like it was aft of the neutral point.
1990, a experienced Bonanza pilot and some of his buddies (engineers at a major automaker) went on a golf weekend, and aft loaded a Bonanza (back seaters, bags behind the back seat). Now this loading worked for the trip out, but now they had less fuel, and the Bonanza is noted for having CG shift aft with fuel burn. On climbout the airplane got away from him in pitch and killed all of them.
CG aft of the neutral point is a bad place. In close coupled birds it can be too fast to keep up with. In bigger airplanes, you might keep up with it for awhile, but a moment of inattention can kill you. In bigger airplanes still, it can probabaly be kept up with, but from there, your margins to tail stall may not be much.
Billski